/* ============================================================
   Computing Technology 7–10 Notes: structural base
   Layout, components and behaviour hooks. Tokens live here; the
   "Data Studio" skin (dot grid, hairline borders, left-edge colour
   bars, mono micro-labels) is layered on top by css/theme.css, which
   every page loads after this file.
   ============================================================ */

/* Fonts, served from this site (css/fonts/): no request goes to a font host. See css/fonts/README.md. */
@font-face { font-family: 'IBM Plex Mono'; font-style: normal; font-weight: 400; font-display: swap; src: url('fonts/ibm-plex-mono-400-latin.woff2') format('woff2'); unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+0304, U+0308, U+0329, U+2000-206F, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD; }
@font-face { font-family: 'IBM Plex Mono'; font-style: normal; font-weight: 500; font-display: swap; src: url('fonts/ibm-plex-mono-500-latin.woff2') format('woff2'); unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+0304, U+0308, U+0329, U+2000-206F, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD; }
@font-face { font-family: 'IBM Plex Mono'; font-style: normal; font-weight: 600; font-display: swap; src: url('fonts/ibm-plex-mono-600-latin.woff2') format('woff2'); unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+0304, U+0308, U+0329, U+2000-206F, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD; }
@font-face { font-family: 'IBM Plex Sans'; font-style: normal; font-weight: 400 600; font-display: swap; src: url('fonts/ibm-plex-sans-latin.woff2') format('woff2'); unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+0304, U+0308, U+0329, U+2000-206F, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD; }
@font-face { font-family: 'Space Grotesk'; font-style: normal; font-weight: 500 700; font-display: swap; src: url('fonts/space-grotesk-latin.woff2') format('woff2'); unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+0304, U+0308, U+0329, U+2000-206F, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD; }

/* ── Custom Properties ── */
:root {
  --font-body:      'IBM Plex Sans', system-ui, -apple-system, 'Segoe UI', sans-serif;
  --font-display:   'Space Grotesk', 'IBM Plex Sans', system-ui, sans-serif;
  --font-mono:      'IBM Plex Mono', ui-monospace, 'SFMono-Regular', Menlo, Consolas, monospace;

  --primary:        #0A7C86;   /* teal-cyan */
  --primary-dark:   #075E66;
  --primary-light:  #E3F4F5;
  --secondary:      #0E9AA7;
  --accent:         #E8A317;   /* signal amber: highlights, KPI deltas, focus marks */

  --sd:         #6D3FD9;   /* violet */
  --sd-light:   #EFE9FD;
  --sd-dark:    #5B2EC4;

  --eis:         #0E7490;   /* cyan */
  --eis-light:   #E0F2F7;
  --eis-dark:    #0B5C72;

  --core:           #334155;   /* slate: resources */
  --core-light:     #E8EDF3;

  --danger:         #DC2626;
  --warning:        #D97706;
  --success:        #16A34A;
  --info:           #0891B2;

  --bg:             #F3F6FA;   /* cool mist */
  --bg-secondary:   #E9EEF5;
  --bg-tertiary:    #F8FAFC;
  --surface:        #FFFFFF;
  --surface-hover:  #F0F4F9;
  --border:         #DCE3EC;   /* hairline */
  --border-strong:  #C3CDDA;

  --text-primary:   #0B1B2E;   /* ink */
  --text-secondary: #44546A;
  --text-muted:     #52607A;   /* darkened again so it passes WCAG AA (4.5:1) on the grey page of light mode */
  --text-inverse:   #F3F6FA;

  --nav-bg:         #0B1B2E;
  --nav-text:       #C5D2E2;
  --nav-active:     #0A7C86;

  --shadow-sm:   0 1px 2px 0 rgba(11,27,46,.05);
  --shadow-md:   0 4px 10px -2px rgba(11,27,46,.10), 0 2px 4px -2px rgba(11,27,46,.06);
  --shadow-lg:   0 12px 24px -6px rgba(11,27,46,.16), 0 4px 8px -4px rgba(11,27,46,.08);
  --shadow-xl:   0 20px 36px -8px rgba(11,27,46,.20), 0 8px 12px -6px rgba(11,27,46,.10);

  /* Small radii: this is a dashboard, not a sticker sheet */
  --radius-sm:   4px;
  --radius-md:   6px;
  --radius-lg:   8px;
  --radius-xl:   8px;
  --radius-2xl:  12px;
  --radius-full: 4px;

  --transition: 160ms cubic-bezier(.4,0,.2,1);

  /* ── Z-index scale ── */
  --z-base:     1;
  --z-raised:   2;
  --z-dropdown: 100;
  --z-sticky:   900;
  --z-navbar:   1000;
  --z-mobile:   999;
  --z-modal:    2000;
  --z-toast:    2001;
  --z-skip:     10000;
}

/* Dark mode: deep navy with teal signal */
[data-theme="dark"] {
  --primary:        #36C2CC;
  --primary-dark:   #22A3AD;
  --primary-light:  #0F2A38;
  --secondary:      #5AD1D9;
  --accent:         #F5B83D;

  --sd:         #A78BFA;
  --sd-light:   #1E1838;
  --sd-dark:    #C4B5FD;

  --eis:         #38BDF8;
  --eis-light:   #0C2536;
  --eis-dark:    #7DD3FC;

  --core:           #94A3B8;
  --core-light:     #1A2536;

  --bg:             #0A1220;
  --bg-secondary:   #0F1A2C;
  --bg-tertiary:    #0D1626;
  --surface:        #111C2E;
  --surface-hover:  #17243A;
  --border:         #22324A;
  --border-strong:  #33465F;

  --text-primary:   #E8EEF6;
  --text-secondary: #A9B8CC;
  --text-muted:     #7D8DA3;

  --shadow-sm:   0 1px 2px 0 rgba(0,0,0,.35);
  --shadow-md:   0 4px 10px -2px rgba(0,0,0,.45), 0 2px 4px -2px rgba(0,0,0,.35);
  --shadow-lg:   0 12px 24px -6px rgba(0,0,0,.55), 0 4px 8px -4px rgba(0,0,0,.4);
  --shadow-xl:   0 20px 36px -8px rgba(0,0,0,.6), 0 8px 12px -6px rgba(0,0,0,.45);
}

/* ── Reset & Base ── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html {
  /* Stop iOS Safari enlarging paragraph text in landscape; it skips buttons such as the
     glossary terms (.gloss), which then look smaller than the text around them */
  -webkit-text-size-adjust: 100%;
  text-size-adjust: 100%;
  scroll-behavior: smooth;
  /* Keep anchor / TOC jump targets clear of the 65px sticky navbar */
  scroll-padding-top: 5rem;
  font-size: 16px;
  /* Firefox branded scrollbar */
  scrollbar-width: thin;
  scrollbar-color: rgba(10,124,134,.35) transparent;
}
[data-theme="dark"] html {
  scrollbar-color: rgba(54,194,204,.40) transparent;
}

/* ── Brand text selection ── */
::selection {
  background: rgba(10, 124, 134, .18);
  color: var(--text-primary);
}
[data-theme="dark"] ::selection {
  background: rgba(54, 194, 204, .32);
  color: #fff;
}

/* ── Branded WebKit scrollbar (sidebar keeps its own thinner rule) ── */
::-webkit-scrollbar { width: 12px; height: 12px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb {
  background: rgba(10,124,134,.30);
  border-radius: 8px;
  border: 3px solid transparent;
  background-clip: content-box;
}
::-webkit-scrollbar-thumb:hover {
  background: rgba(10,124,134,.5);
  background-clip: content-box;
}
[data-theme="dark"] ::-webkit-scrollbar-thumb {
  background: rgba(54,194,204,.30);
  background-clip: content-box;
}
[data-theme="dark"] ::-webkit-scrollbar-thumb:hover {
  background: rgba(54,194,204,.5);
  background-clip: content-box;
}

/* ── Skip Link (Accessibility) ── */
.skip-link {
  position: absolute;
  top: -100%;
  left: 1rem;
  background: var(--primary);
  color: #ffffff;
  padding: 0.75rem 1.5rem;
  border-radius: 0 0 var(--radius-md) var(--radius-md);
  font-size: .9rem;
  font-weight: 600;
  text-decoration: none;
  z-index: var(--z-skip);
  transition: top 200ms ease;
}

.skip-link:focus {
  top: 0;
  outline: 2px solid #ffffff;
  outline-offset: 2px;
}

/* ── Focus Indicators (Accessibility) ── */
a:focus-visible,
button:focus-visible,
.topic-card:focus-visible,
.nav-links a:focus-visible,
.toc-list a:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 2px;
  border-radius: var(--radius-sm);
}

.btn:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 3px;
}

.search-input:focus-visible {
  outline: none; /* handled by box-shadow */
}

body {
  margin: 0;
  font-family: var(--font-body);
  background: var(--bg);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
  transition: background var(--transition), color var(--transition);
}

/* ── Navigation ── */
.navbar {
  position: sticky;
  top: 0;
  z-index: var(--z-navbar);
  background: rgba(20,20,25,.88);
  border-bottom: 1px solid rgba(255,255,255,.08);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  transition: box-shadow 240ms ease, background 240ms ease;
  /* overflow: visible so dropdown menus can extend below the bar.
     Do NOT use overflow:hidden/auto/scroll — those break position:sticky. */
  overflow: visible;
}

/* Set from JS once the page is scrolled */
.navbar.scrolled {
  background: rgba(20,20,25,.96);
  box-shadow: 0 8px 24px rgba(0,0,0,.18);
}

/* ── Reading Progress Bar ── */
.reading-progress {
  position: absolute;
  bottom: 0;
  left: 0;
  height: 2px;
  width: calc(var(--scroll-pct, 0) * 1%);
  background: linear-gradient(90deg, var(--primary), var(--secondary));
  transition: width 80ms linear;
  pointer-events: none;
  opacity: 0;
}

.has-toc .reading-progress { opacity: 1; }

.nav-inner {
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
  gap: 1rem;
}

.nav-brand {
  display: flex;
  align-items: center;
  gap: .75rem;
  text-decoration: none;
  flex-shrink: 0;
}

.nav-logo {
  width: 36px;
  height: 36px;
  background: transparent;
  border: 1px solid rgba(255,255,255,.22);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-display);
  font-size: 1rem;
  font-weight: 600;
  color: #F3F6FA;
  letter-spacing: -.05em;
  transition: border-color var(--transition), background var(--transition);
}
.nav-brand:hover .nav-logo {
  border-color: rgba(255,255,255,.45);
  background: rgba(255,255,255,.06);
}

.nav-title {
  font-weight: 700;
  font-size: .95rem;
  color: #E8EEF6;
  line-height: 1.2;
}

.nav-subtitle {
  font-size: .7rem;
  color: var(--text-muted);
  font-weight: 400;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: .25rem;
  list-style: none;
  flex: 1;
  justify-content: center;
}

.nav-links a {
  display: flex;
  align-items: center;
  gap: .375rem;
  padding: .4rem .75rem;
  border-radius: var(--radius-md);
  text-decoration: none;
  font-size: .85rem;
  font-weight: 500;
  color: var(--nav-text);
  transition: all var(--transition);
  white-space: nowrap;
}

.nav-links a:hover,
.nav-links a.active {
  background: rgba(255,255,255,.1);
  color: #FFFFFF;
}

.nav-links .badge {
  font-size: .65rem;
  font-weight: 700;
  padding: .1rem .4rem;
  border-radius: var(--radius-full);
  letter-spacing: .03em;
}

/* ── Badge base colours (light-bg contexts: topic pages, main content) ── */
.badge-sd { background: rgba(109,63,217,.15); color: var(--sd-dark); border: 1px solid rgba(109,63,217,.3); }
.badge-eis { background: rgba(14,116,144,.15); color: var(--eis-dark); border: 1px solid rgba(14,116,144,.3); }
[data-theme="dark"] .badge-sd { background: rgba(109,63,217,.2); color: #C4B5FD; border-color: rgba(109,63,217,.35); }
[data-theme="dark"] .badge-eis { background: rgba(14,116,144,.2); color: #7DD3FC; border-color: rgba(14,116,144,.35); }

/* ── Badge colours — nav context (always dark bg, needs light text) ── */
.nav-links .badge-sd,
.nav-dropdown-btn .badge-sd {
  color: #C4B5FD;
  background: rgba(109,63,217,.25);
  border-color: rgba(109,63,217,.4);
}
.nav-links .badge-eis,
.nav-dropdown-btn .badge-eis {
  color: #7DD3FC;
  background: rgba(14,116,144,.25);
  border-color: rgba(14,116,144,.4);
}

/* ── Nav Dropdown ── */
.nav-dropdown {
  position: relative;
}

.nav-dropdown-btn {
  display: inline-flex;
  align-items: center;
  gap: .375rem;
  padding: .4rem .75rem;
  border-radius: var(--radius-md);
  background: none;
  border: none;
  font-family: inherit;
  font-size: .85rem;
  font-weight: 500;
  color: var(--nav-text);
  cursor: pointer;
  transition: background var(--transition), color var(--transition);
  white-space: nowrap;
  line-height: 1;
}

.nav-dropdown-btn:hover,
.nav-dropdown.open .nav-dropdown-btn {
  background: rgba(255,255,255,.1);
  color: #FFFFFF;
}

/* Active year group — tinted trigger so it's clear where you are */
.nav-dropdown.nav-dropdown--has-active.nav-dropdown-sd .nav-dropdown-btn {
  background: rgba(109,63,217,.18);
  color: #C4B5FD;
  font-weight: 600;
}
.nav-dropdown.nav-dropdown--has-active.nav-dropdown-eis .nav-dropdown-btn {
  background: rgba(14,116,144,.18);
  color: #7DD3FC;
  font-weight: 600;
}

/* Active item in menu — small coloured dot + bold text */
.nav-dropdown-menu a.active::before {
  content: '';
  width: 5px; height: 5px;
  border-radius: 50%;
  flex-shrink: 0;
  margin-right: -.125rem; /* optical balance */
}
.nav-dropdown-sd .nav-dropdown-menu a.active::before { background: var(--sd); }
.nav-dropdown-eis .nav-dropdown-menu a.active::before { background: var(--eis); }

.nav-chevron {
  flex-shrink: 0;
  width: 11px;
  height: 11px;
  transition: transform 220ms cubic-bezier(.4,0,.2,1);
  opacity: .7;
}
.nav-dropdown.open .nav-chevron {
  transform: rotate(180deg);
  opacity: 1;
}

/* ── Dropdown menu panel ── */
/* Pure-transition approach: no keyframe/transition property conflict.
   The visibility delay trick: `0s 180ms` on hide keeps the element
   screen-reader-invisible only after the fade is done; `0s 0s` on show
   makes it visible immediately so the fade is visible. */
.nav-dropdown-menu {
  position: absolute;
  top: calc(100% + 6px);
  left: 50%;
  transform: translateX(-50%) translateY(-8px);
  min-width: 230px;
  background: #111C2E;
  border: 1px solid rgba(255,255,255,.1);
  border-radius: var(--radius-xl);
  padding: .375rem;
  opacity: 0;
  pointer-events: none;
  visibility: hidden;
  box-shadow: 0 16px 40px rgba(0,0,0,.45), 0 0 0 1px rgba(255,255,255,.04);
  z-index: var(--z-dropdown);
  transition: opacity 180ms ease,
              transform 180ms cubic-bezier(.4,0,.2,1),
              visibility 0s linear 180ms;
}

.nav-dropdown-menu::before {
  content: '';
  position: absolute;
  top: -1px; left: 0; right: 0;
  height: 2px;
  border-radius: var(--radius-xl) var(--radius-xl) 0 0;
}
.nav-dropdown-sd .nav-dropdown-menu::before { background: linear-gradient(90deg, var(--sd), #0A7C86); }
.nav-dropdown-eis .nav-dropdown-menu::before { background: linear-gradient(90deg, var(--eis), #06B6D4); }

.nav-dropdown.open .nav-dropdown-menu {
  opacity: 1;
  pointer-events: auto;
  visibility: visible;
  transform: translateX(-50%) translateY(0);
  transition: opacity 180ms ease,
              transform 180ms cubic-bezier(.4,0,.2,1),
              visibility 0s linear 0s;
}

.nav-dropdown-menu a {
  display: flex;
  align-items: center;
  gap: .625rem;
  padding: .6rem .875rem;
  border-radius: var(--radius-lg);
  text-decoration: none;
  font-size: .85rem;
  font-weight: 500;
  color: #8FA0B8;
  transition: background var(--transition), color var(--transition), transform var(--transition);
  white-space: nowrap;
}

.nav-dropdown-menu a:hover {
  color: #FFFFFF;
  transform: translateX(3px);
}
.nav-dropdown-sd .nav-dropdown-menu a:hover { background: rgba(109,63,217,.15); }
.nav-dropdown-eis .nav-dropdown-menu a:hover { background: rgba(14,116,144,.15); }

.nav-dropdown-menu a.active {
  color: #FFFFFF;
  font-weight: 600;
}
.nav-dropdown-sd .nav-dropdown-menu a.active { background: rgba(109,63,217,.2); }
.nav-dropdown-eis .nav-dropdown-menu a.active { background: rgba(14,116,144,.2); }

/* ── Focus ring on dropdown button ── */
.nav-dropdown-btn:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 2px;
  border-radius: var(--radius-md);
}



.nav-actions {
  display: flex;
  align-items: center;
  gap: .5rem;
  flex-shrink: 0;
}

.btn-icon {
  width: 36px;
  height: 36px;
  border-radius: var(--radius-md);
  border: 1px solid rgba(255,255,255,.1);
  background: rgba(255,255,255,.05);
  color: var(--nav-text);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: .9rem;
  transition: all var(--transition);
}

.btn-icon svg,
.btn-mobile-theme svg {
  width: 16px;
  height: 16px;
  stroke: currentColor;
  fill: none;
  stroke-width: 1.75;
  stroke-linecap: round;
  stroke-linejoin: round;
  transition: transform 320ms cubic-bezier(.34,1.56,.64,1);
}

#theme-toggle:hover svg { transform: rotate(-18deg); }

.btn-icon:hover {
  background: rgba(255,255,255,.12);
  color: #FFFFFF;
}

.hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  cursor: pointer;
  padding: .5rem;
}

.hamburger span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--nav-text);
  border-radius: 2px;
  transition: all var(--transition);
}

/* Mobile menu */
.mobile-menu {
  position: fixed;
  inset: 64px 0 0 0;
  background: var(--nav-bg);
  z-index: var(--z-mobile);
  padding: 1.5rem;
  overflow-y: auto;
  border-top: 1px solid rgba(255,255,255,.08);
  transform: translateX(-100%);
  opacity: 0;
  visibility: hidden;
  transition: transform 280ms cubic-bezier(.4,0,.2,1),
              opacity    280ms cubic-bezier(.4,0,.2,1),
              visibility 280ms;
}

.mobile-menu.open {
  transform: translateX(0);
  opacity: 1;
  visibility: visible;
}

.mobile-menu-section {
  margin-bottom: 1.5rem;
}

.mobile-menu-label {
  font-size: .7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .08em;
  color: var(--text-muted);
  margin-bottom: .5rem;
  padding: 0 .5rem;
}

.mobile-menu a {
  display: flex;
  align-items: center;
  gap: .75rem;
  padding: .75rem .75rem;
  border-radius: var(--radius-md);
  text-decoration: none;
  color: var(--nav-text);
  font-size: .9rem;
  font-weight: 500;
  transition: all var(--transition);
  margin-bottom: .25rem;
}

.mobile-menu a:hover { background: rgba(255,255,255,.07); color: #FFFFFF; }

/* ── Layout ── */
.page-layout {
  display: grid;
  grid-template-columns: 260px 1fr;
  grid-template-rows: 1fr;
  max-width: 1280px;
  margin: 0 auto;
  min-height: calc(100vh - 64px);
  padding: 0 1.5rem;
  gap: 2rem;
}

.sidebar {
  position: sticky;
  top: 80px;
  height: calc(100vh - 96px);
  overflow-y: auto;
  padding: 1.5rem 0;
}

.sidebar::-webkit-scrollbar { width: 4px; }
.sidebar::-webkit-scrollbar-track { background: transparent; }
.sidebar::-webkit-scrollbar-thumb { background: var(--border); border-radius: var(--radius-full); }

.toc-title {
  font-size: .7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .08em;
  color: var(--text-muted);
  margin-bottom: .75rem;
  padding: 0 .5rem;
}

.sidebar-label {
  font-size: .75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .08em;
  color: #8A5A00;
  padding: .75rem 0 .1rem;
  list-style: none; /* Ensure no bullets if used in a list */
}

[data-theme="dark"] .sidebar-label { color: var(--accent); }

.sidebar-label:first-child {
  padding-top: .25rem;
}

.toc-list { list-style: none; }

.toc-list a {
  display: block;
  padding: .4rem .75rem;
  border-radius: var(--radius-md);
  text-decoration: none;
  font-size: .82rem;
  color: var(--text-secondary);
  transition: all var(--transition);
  border-left: 2px solid transparent;
}

.toc-list a:hover {
  background: var(--bg-secondary);
  color: var(--text-primary);
  border-left-color: var(--primary);
}

.toc-list a.active {
  background: var(--primary-light);
  color: var(--primary);
  border-left: 3px solid var(--primary);
  font-weight: 600;
  padding-left: calc(.75rem - 1px);
}

.toc-list .toc-sub a {
  padding-left: 1.75rem;
  font-size: .78rem;
}

.page-content {
  padding: clamp(1.5rem, 2vw, 2rem) 0 clamp(2rem, 3vw, 4rem);
  min-width: 0;
}

/* ── Hero Section ── */
.hero {
  background: #0B1B2E;
  padding: clamp(3rem, 5vw, 5.5rem) 1.5rem;
  text-align: center;
  position: relative;
  overflow: hidden;
  margin-bottom: 1rem;
}

/* Quiet depth: one cool glow, one warm — plus a cursor-following light
   driven by --hx/--hy custom properties set from JS. */
.hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background-image:
    radial-gradient(620px 420px at var(--hx, 50%) var(--hy, 38%), rgba(120,140,225,.13) 0%, transparent 70%),
    radial-gradient(circle at 12% 88%, rgba(10,124,134,.16) 0%, transparent 52%),
    radial-gradient(circle at 88% 10%, rgba(176,140,61,.10) 0%, transparent 46%);
  transition: background-position 120ms linear;
}

.hero-grid {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(255,255,255,.045) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255,255,255,.045) 1px, transparent 1px);
  background-size: 44px 44px;
  -webkit-mask-image: radial-gradient(ellipse 75% 85% at 50% 40%, #000 25%, transparent 78%);
  mask-image: radial-gradient(ellipse 75% 85% at 50% 40%, #000 25%, transparent 78%);
}

.hero-inner {
  position: relative;
  max-width: 900px;
  margin: 0 auto;
}

.hero-pill {
  display: inline-flex;
  align-items: center;
  gap: .5rem;
  background: transparent;
  border: 1px solid rgba(255,255,255,.16);
  color: #B9B9C5;
  padding: .4rem 1.1rem;
  border-radius: var(--radius-full);
  font-size: .72rem;
  font-weight: 600;
  letter-spacing: .14em;
  text-transform: uppercase;
  margin-bottom: 2rem;
}

.hero h1 {
  font-family: var(--font-display);
  font-size: clamp(2.3rem, 5.5vw, 4rem);
  font-weight: 600;
  color: #F3F6FA;
  line-height: 1.12;
  margin-bottom: 1.5rem;
  letter-spacing: -.015em;
}

.hero h1 span {
  font-style: italic;
  font-weight: 500;
  color: #A8B7EE;
}

.hero p {
  font-size: 1.05rem;
  color: #9A9AA6;
  max-width: 580px;
  margin: 0 auto 2.75rem;
  line-height: 1.75;
}

.hero-stats {
  display: flex;
  justify-content: center;
  gap: 2.5rem;
  margin-bottom: 2.5rem;
}

.hero-stat {
  text-align: center;
  position: relative;
}

/* Thin divider between hero stats */
.hero-stat + .hero-stat::before {
  content: '';
  position: absolute;
  left: -1.25rem;   /* sits in the middle of the 2.5rem gap */
  top: 15%;
  height: 70%;
  width: 1px;
  background: rgba(255,255,255,.14);
}

.hero-stat-num {
  font-family: var(--font-display);
  font-size: 2.1rem;
  font-weight: 600;
  color: #F3F6FA;
  line-height: 1;
}

.hero-stat-label {
  font-size: .78rem;
  color: #9A9AA6;
  letter-spacing: .02em;
  margin-top: .4rem;
}

.hero-cta {
  display: flex;
  gap: 1rem;
  justify-content: center;
  flex-wrap: wrap;
}

/* ── Buttons ── */
.btn {
  display: inline-flex;
  align-items: center;
  gap: .5rem;
  padding: .7rem 1.5rem;
  border-radius: var(--radius-full);
  font-size: .9rem;
  font-weight: 600;
  text-decoration: none;
  cursor: pointer;
  transition: all var(--transition);
  border: none;
  white-space: nowrap;
}

.btn-primary {
  background: #F3F6FA;
  color: #0B1B2E;
  box-shadow: 0 1px 2px rgba(0,0,0,.25);
}

.btn-primary:hover {
  background: #FFFFFF;
  transform: translateY(-1px);
  box-shadow: 0 6px 18px rgba(0,0,0,.3);
}

.btn-primary .btn-arrow {
  display: inline-block;
  transition: transform var(--transition);
}

.btn-primary:hover .btn-arrow {
  transform: translateX(3px);
}

.btn-outline {
  background: transparent;
  color: #C5D2E2;
  border: 1px solid rgba(255,255,255,.22);
}

.btn-outline:hover {
  background: rgba(255,255,255,.07);
  border-color: rgba(255,255,255,.4);
  color: #FFFFFF;
}

/* ── Main Content Area ── */
.main-content {
  max-width: 1280px;
  margin: 0 auto;
  padding: clamp(1.5rem, 2vw, 2.5rem) 1.5rem clamp(2rem, 2.5vw, 3rem) 1.5rem;
}

/* ── Section Headers ── */
.section-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 2rem;
  padding-bottom: 1.25rem;
  border-bottom: 1px solid var(--border);
  gap: 1rem;
}

.section-title {
  font-family: var(--font-display);
  font-size: 1.45rem;
  font-weight: 600;
  letter-spacing: -.01em;
  color: var(--text-primary);
  display: flex;
  align-items: center;
  gap: .75rem;
}

.section-title .year-badge {
  font-size: .7rem;
  font-weight: 700;
  padding: .25rem .6rem;
  border-radius: var(--radius-full);
  text-transform: uppercase;
  letter-spacing: .05em;
}

.year-badge-sd { background: var(--sd-light); color: var(--sd-dark); }
.year-badge-eis { background: var(--eis-light); color: var(--eis-dark); }

[data-theme="dark"] .year-badge-sd { background: rgba(109,63,217,.2); color: #C4B5FD; }
[data-theme="dark"] .year-badge-eis { background: rgba(14,116,144,.2); color: #7DD3FC; }

/* ── Topic Cards ── */
.topics-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(310px, 1fr));
  gap: 1.5rem;
  margin-bottom: 3.5rem;
}

.topic-card {
  display: flex;
  flex-direction: column;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  padding: 1.75rem;
  text-decoration: none;
  color: var(--text-primary);
  transition: all var(--transition);
  position: relative;
  overflow: clip;   /* clip: no scroll context, no corner-cropping on transform */
  height: 100%;
  box-shadow: var(--shadow-sm);
}

.topic-card::before {
  content: '';
  position: absolute;
  inset: 0;
  opacity: 0;
  transition: opacity var(--transition);
}

.topic-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-lg);
  border-color: transparent;
}

.topic-card.sd {
  border-top: 3px solid var(--sd);
  background: linear-gradient(150deg, var(--surface) 75%, rgba(109,63,217,.07));
}
.topic-card.eis {
  border-top: 3px solid var(--eis);
  background: linear-gradient(150deg, var(--surface) 75%, rgba(14,116,144,.07));
}

.topic-card.sd:hover { box-shadow: 0 12px 30px rgba(109,63,217,.2); }
.topic-card.eis:hover { box-shadow: 0 12px 30px rgba(14,116,144,.2); }

.card-icon {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 1.25rem;
  flex-shrink: 0;
}

.card-icon svg {
  width: 22px;
  height: 22px;
  stroke: currentColor;
  fill: none;
  stroke-width: 1.6;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.sd .card-icon { background: var(--sd-light); color: var(--sd-dark); }
.eis .card-icon { background: var(--eis-light); color: var(--eis-dark); }

[data-theme="dark"] .sd .card-icon { background: rgba(109,63,217,.15); color: #C4B5FD; }
[data-theme="dark"] .eis .card-icon { background: rgba(14,116,144,.15); color: #7DD3FC; }

.card-title {
  font-family: var(--font-display);
  font-size: 1.2rem;
  font-weight: 600;
  margin-bottom: 0.75rem;
  color: var(--text-primary);
  line-height: 1.3;
}

.card-desc {
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.6;
  flex: 1;
  margin-bottom: 1.25rem;
}

.card-meta {
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: .78rem;
  color: var(--text-muted);
}

.card-topics {
  display: flex;
  gap: .375rem;
  flex-wrap: wrap;
}

.topic-tag {
  font-size: .7rem;
  padding: .2rem .55rem;
  border-radius: var(--radius-full);
  background: var(--bg-secondary);
  color: var(--text-muted);
  border: 1px solid var(--border);
  font-weight: 500;
}

/* Year-tinted tags */
.sd .topic-tag {
  background: rgba(109,63,217,.08);
  color: var(--sd-dark);
  border-color: rgba(109,63,217,.22);
}
.eis .topic-tag {
  background: rgba(14,116,144,.08);
  color: var(--eis-dark);
  border-color: rgba(14,116,144,.22);
}
[data-theme="dark"] .sd .topic-tag { color: #C4B5FD; border-color: rgba(109,63,217,.28); }
[data-theme="dark"] .eis .topic-tag { color: #7DD3FC; border-color: rgba(14,116,144,.28); }

.card-arrow {
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--text-muted);
  transition: transform var(--transition), color var(--transition);
}

.topic-card:hover .card-arrow { transform: translateX(5px); }
.topic-card.sd:hover .card-arrow { color: var(--sd); }
.topic-card.eis:hover .card-arrow { color: var(--eis); }

/* ── Feature Banners ── */
.features-bar {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: clamp(1rem, 2vw, 1.5rem);
  padding: clamp(1.75rem, 2.5vw, 2.25rem) 1.5rem;
  background: var(--bg-secondary);
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
}

.feature-item {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.feature-icon {
  width: 44px;
  height: 44px;
  background: var(--primary-light);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.25rem;
  flex-shrink: 0;
}

[data-theme="dark"] .feature-icon { background: rgba(10,124,134,.15); }

.feature-text strong {
  display: block;
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 0.25rem;
}

.feature-text span {
  font-size: 0.8rem;
  color: var(--text-secondary);
  line-height: 1.4;
}

/* ── Topic Page Header ── */
.topic-header {
  background: linear-gradient(135deg, #0B1B2E, #111C2E);
  padding: clamp(1.75rem, 2.5vw, 3rem) 1.5rem;
  position: relative;
  overflow: hidden;
  width: 100%;
  box-sizing: border-box;
}

.topic-header::before {
  content: '';
  position: absolute;
  inset: 0;
  background-image:
    radial-gradient(circle at 30% 50%, rgba(10,124,134,.12) 0%, transparent 60%);
}

.topic-header-inner {
  position: relative;
  max-width: 1280px;
  margin: 0 auto;
}

.topic-breadcrumb {
  display: flex;
  align-items: center;
  gap: .5rem;
  font-size: .8rem;
  color: #8FA0B8;
  margin-bottom: 1rem;
}

.topic-breadcrumb a {
  color: #8FA0B8;
  text-decoration: none;
  transition: color var(--transition);
}

.topic-breadcrumb a:hover { color: #E1E9F3; }

.topic-header h1 {
  font-family: var(--font-display);
  font-size: clamp(1.85rem, 4vw, 2.9rem);
  font-weight: 600;
  color: #F3F6FA;
  letter-spacing: -.015em;
  line-height: 1.18;
  margin-bottom: .75rem;
}

.topic-header-meta {
  display: flex;
  align-items: center;
  gap: 1rem;
  flex-wrap: wrap;
  margin-top: 1rem;
}

.meta-pill {
  display: inline-flex;
  align-items: center;
  gap: .375rem;
  padding: .3rem .75rem;
  border-radius: var(--radius-full);
  font-size: .78rem;
  font-weight: 600;
  background: rgba(255,255,255,.08);
  color: #C5D2E2;
  border: 1px solid rgba(255,255,255,.12);
}

.meta-pill.sd { background: rgba(109,63,217,.15); color: #C4B5FD; border-color: rgba(109,63,217,.3); }
.meta-pill.eis { background: rgba(14,116,144,.15); color: #7DD3FC; border-color: rgba(14,116,144,.3); }

/* ── Content Typography ── */
.content-body h2 {
  font-family: var(--font-display);
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--text-primary);
  margin: 2.5rem 0 1rem;
  padding-top: .5rem;
  letter-spacing: -.01em;
  display: flex;
  align-items: center;
  gap: .75rem;
}

/* Light mode h2 — deep brand-ink blue on warm paper (tied to --primary, not cold grey) */
[data-theme="light"] .content-body h2:not(.syllabus-phase) {
  color: #0B1B2E;
  padding-bottom: .55rem;
  border-bottom: 1px solid;
  border-image: linear-gradient(90deg, rgba(10,124,134,.4) 0%, rgba(176,140,61,.22) 42%, transparent 82%) 1;
}

/* Dark mode h2 — bright ink, cool hairline gradient underline */
[data-theme="dark"] .content-body h2:not(.syllabus-phase) {
  color: #f3f5fb;
  padding-bottom: .55rem;
  border-bottom: 1px solid;
  border-image: linear-gradient(90deg, rgba(54,194,204,.45) 0%, rgba(203,168,92,.24) 42%, transparent 82%) 1;
}

/* ── Syllabus Phase Heading (minor — individual syllabus items) ── */
.content-body h2.syllabus-phase {
  background: linear-gradient(135deg, var(--primary-dark) 0%, var(--primary) 55%, var(--secondary) 100%);
  color: #fff;
  padding: 1.2rem 1.25rem 0.65rem 1.25rem;
  border-radius: var(--radius-lg);
  margin: 1.5rem 0 0;
  font-size: clamp(1rem, 1.5vw, 1.15rem);
  font-weight: 800;
  letter-spacing: -.02em;
  line-height: 1.5;
  box-shadow: 0 4px 14px rgba(10, 124, 134, 0.25);
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.35rem 0.5rem;
  border: 1px solid rgba(10,124,134,0.4);
  border-left: 6px solid var(--accent);
  cursor: pointer;
  user-select: none;
  transition: all 260ms cubic-bezier(.4,0,.2,1);
  position: relative;
  overflow: hidden;
}

/* Subtle top-left shine for depth */
.content-body h2.syllabus-phase::before {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, rgba(255,255,255,0.14) 0%, transparent 55%);
  pointer-events: none;
  border-radius: inherit;
}

.content-body > section:first-child h2 {
  margin-top: 0;
}

.content-body h2.syllabus-phase:hover {
  box-shadow: 0 6px 24px rgba(10, 124, 134, 0.4);
  transform: translateX(3px);
  filter: brightness(1.05);
}

.content-body h2.syllabus-phase.section-collapsed {
  margin-bottom: 0;
  box-shadow: 0 2px 8px rgba(10, 124, 134, 0.14);
  border-radius: var(--radius-md);
}

.content-body h2.syllabus-phase::before {
  display: none;
}

/* Outcome badges inside the header bar */
h2.syllabus-phase .outcome-subtitle {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.35rem;
  margin: 0;
  padding: 0;
  background: none;
  border: none;
  font-size: 0.65rem;
  order: 1;
  flex-basis: 100%;
}

h2.syllabus-phase .outcome-badge {
  background: rgba(255,255,255,.22);
  color: #fff;
  font-size: 0.6rem;
  padding: 0.2rem 0.6rem;
  box-shadow: none;
}

h2.syllabus-phase .outcome-badge:hover {
  background: rgba(255,255,255,.35);
  transform: none;
  box-shadow: none;
}

/* Light mode syllabus-phase: lighter, less saturated feel */
[data-theme="light"] .content-body h2.syllabus-phase {
  background: linear-gradient(135deg, #0A7C86 0%, #0B8C97 55%, #0E9AA7 100%);
  box-shadow: 0 3px 12px rgba(10, 124, 134, 0.18);
  border: 1px solid rgba(10,124,134,0.25);
}

[data-theme="light"] .content-body h2.syllabus-phase:hover {
  box-shadow: 0 5px 20px rgba(10, 124, 134, 0.28);
}

[data-theme="dark"] .content-body h2.syllabus-phase {
  background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
  box-shadow: 0 3px 14px rgba(10, 124, 134, 0.18);
}

[data-theme="dark"] h2.syllabus-phase .outcome-badge {
  background: rgba(255,255,255,.18);
}

/* Syllabus concept statement inside the header bar */
h2.syllabus-phase .syllabus-concept {
  flex-basis: 100%;
  order: 2;
  margin: 0.1rem 0 0;
  padding: 0;
  font-size: 0.72rem;
  font-weight: 400;
  color: rgba(255, 255, 255, 0.82);
  line-height: 1.45;
  letter-spacing: 0;
}

h2.syllabus-phase .syllabus-concept em {
  font-style: italic;
}

h2.syllabus-phase .syllabus-concept strong {
  font-weight: 700;
  color: #fff;
}

/* Chevron indicator (injected by JS) */
.section-chevron {
  margin-left: auto;
  flex-shrink: 0;
  width: 24px;
  height: 24px;
  border-radius: 50%;
  background: rgba(255,255,255,.2);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: transform 360ms cubic-bezier(.4,0,.2,1),
              background 220ms;
}

.section-chevron svg {
  display: block;
  width: 16px;
  height: 16px;
  stroke: rgba(255,255,255,.95);
  fill: none;
  stroke-width: 2.5;
  stroke-linecap: round;
  stroke-linejoin: round;
}

h2.syllabus-phase.section-collapsed .section-chevron {
  transform: rotate(-90deg);
}

h2.syllabus-phase:hover .section-chevron {
  background: rgba(255,255,255,.35);
}

/* ── Collapsible Section Body ── */
.section-body {
  display: grid;
  grid-template-rows: 1fr;
  overflow: hidden;              /* clips leaking margins/padding */
  transition: grid-template-rows 380ms cubic-bezier(.4,0,.2,1),
              background 260ms cubic-bezier(.4,0,.2,1);
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-top: none;
  border-radius: 0 0 var(--radius-lg) var(--radius-lg);
  margin-top: 0;
  box-shadow: inset 0 3px 8px rgba(10,124,134,0.04);  /* subtle inner depth */
}

.section-body.section-collapsed {
  grid-template-rows: 0fr;
  background: transparent;
  border-radius: 0;
  margin-top: 0;
  max-height: 0;
}

/* Clear gap between sections (collapsed or expanded) */
.part-group-inner > section + .divider + section > h2.syllabus-phase,
.part-group-inner > section + section > h2.syllabus-phase {
  margin-top: 0.75rem;
}

/* Ensure first h2 in section doesn't have excess top margin */
section > h2.syllabus-phase:first-child {
  margin-top: 0;
}

.section-body-inner {
  min-height: 0;                 /* allows grid row to compress to 0 */
  min-width: 0;                  /* allows grid item to shrink so wide tables scroll instead of widening the page */
  overflow: hidden;              /* establishes BFC, prevents content leaking when collapsed */
  padding: 1.75rem;
}

/* Subtle dividers between h3 blocks within a section */
.section-body-inner * + h3,
.content-body section * + h3 {
  border-top: 1px solid var(--border);
  margin-top: 1.5rem;
  padding-top: 1.25rem;
}

/* First h3 in a section body already has padding from the container —
   suppress its own top margin so the gap isn't doubled */
.section-body-inner > h3:first-child {
  margin-top: 0;
}

/* ── Major Syllabus Part Heading (top-level syllabus divisions) ── */
.part-block {
  color: #fff;
  padding: 1.6rem 3.5rem 1.2rem 2rem;
  border-radius: var(--radius-md);
  margin: 2.5rem 0 1.75rem;
  border-left: 6px solid var(--accent);
  display: flex;
  flex-direction: column;
  gap: .3rem;
  position: relative;
  cursor: pointer;
  user-select: none;
  transition: box-shadow 240ms ease, transform 200ms ease;
}

/* Light mode: refined, less heavy */
[data-theme="light"] .part-block {
  background: linear-gradient(135deg, #1a1a2e 0%, #0A7C86 100%);
  box-shadow: 0 4px 16px rgba(10, 124, 134, 0.2);
}

[data-theme="light"] .part-block:hover {
  box-shadow: 0 8px 28px rgba(10, 124, 134, 0.32);
  transform: translateY(-1px);
}

/* Dark mode: original rich gradient */
[data-theme="dark"] .part-block,
.part-block {
  background: linear-gradient(135deg, #0B1B2E 0%, #0F2A38 50%, var(--primary-dark) 100%);
  box-shadow: 0 8px 28px rgba(10, 124, 134, 0.4);
}

.content-body > .part-block:first-child {
  margin-top: 0;
  margin-bottom: 1.75rem;
}

[data-theme="dark"] .part-block:hover {
  box-shadow: 0 10px 36px rgba(10, 124, 134, 0.55);
  transform: translateY(-1px);
}

.part-block:active { transform: translateY(0); }

.part-block .part-number {
  font-size: .72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .14em;
  opacity: .65;
  color: var(--accent);
}

.part-block .part-name {
  font-family: var(--font-display);
  font-size: 1.5rem;
  font-weight: 600;
  letter-spacing: -.015em;
  line-height: 1.25;
}

/* Chevron injected by JS */
.part-chevron {
  position: absolute;
  right: 1.25rem;
  top: 50%;
  transform: translateY(-50%);
  width: 36px;
  height: 36px;
  background: rgba(255,255,255,.18);
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  transition: background 200ms ease, transform 200ms ease;
}

.part-chevron svg {
  display: block;
  width: 20px;
  height: 20px;
  stroke: rgba(255,255,255,.95);
  stroke-width: 2.5;
  fill: none;
  stroke-linecap: round;
  stroke-linejoin: round;
  transition: transform 380ms cubic-bezier(.4,0,.2,1);
}

.part-block.part-collapsed .part-chevron svg {
  transform: rotate(-90deg);
}

.part-block:hover .part-chevron {
  background: rgba(255,255,255,.3);
}

/* Collapsed indicator: slightly dim the title text */
.part-block.part-collapsed .part-name {
  opacity: .8;
}

/* ── Collapsible Part Group (wraps sections belonging to a part) ── */
.part-group {
  display: grid;
  grid-template-rows: 1fr;
  transition: grid-template-rows 420ms cubic-bezier(.4,0,.2,1);
  margin: 1rem 0;
}

.part-group.part-collapsed {
  grid-template-rows: 0fr;
  margin: 0;
}

.part-group-inner {
  min-height: 0;
  min-width: 0;
  overflow: clip;
  padding: 0 0 1.5rem 0;
  background: transparent;
  border-radius: var(--radius-lg);
  transition: background 260ms cubic-bezier(.4,0,.2,1),
              border-radius 260ms cubic-bezier(.4,0,.2,1);
}

.part-group.part-collapsed .part-group-inner {
  background: transparent;
  border-radius: 0;
  padding: 0;
}

[data-theme="dark"] .part-block {
  background: linear-gradient(135deg, #0B1B2E 0%, var(--primary-dark) 100%);
  box-shadow: 0 8px 28px rgba(10, 124, 134, 0.2);
}

/* ── TOC Part Label Active State ── */
.toc-part-label {
  transition: color 200ms ease, opacity 200ms ease;
}

.toc-part-label.toc-part-active {
  color: var(--primary);
  opacity: 1;
}

/* h2 accent bar — gradient ink, adapts per theme via custom props */
.content-body h2:not(.syllabus-phase)::before {
  content: '';
  display: block;
  width: 5px;
  height: 1.45rem;
  background: linear-gradient(180deg, var(--primary) 0%, var(--accent) 100%);
  border-radius: var(--radius-full);
  flex-shrink: 0;
  box-shadow: 0 1px 4px rgba(10,124,134,.25);
}

[data-theme="dark"] .content-body h2:not(.syllabus-phase)::before {
  box-shadow: 0 0 8px rgba(54,194,204,.35);
}

/* ── h3 — Section sub-headings ── */
.content-body h3 {
  font-family: var(--font-display);
  font-size: clamp(1.05rem, 1.4vw, 1.2rem);
  font-weight: 600;
  color: var(--text-primary);
  margin: 1.75rem 0 .75rem;
  position: relative;
  padding-bottom: 0.6rem;
  padding-left: 0.85rem;
  border-left: 3px solid var(--primary);
}

/* Light mode h3 — rich brand blue, one step lighter than h2 (clear tonal ladder) */
[data-theme="light"] .content-body h3 {
  color: #0B3B45;
  border-left-color: transparent;
  border-image: linear-gradient(180deg, var(--primary) 0%, var(--accent) 100%) 1;
}

[data-theme="light"] .content-body h3::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 58%;
  height: 2px;
  background: linear-gradient(90deg, var(--primary) 0%, var(--accent) 55%, transparent 100%);
  border-radius: var(--radius-full);
  opacity: 0.3;
}

/* Dark mode h3 — gradient ink bar + glow underline */
[data-theme="dark"] .content-body h3 {
  color: #f3f5fb;
  border-left-color: transparent;
  border-image: linear-gradient(180deg, var(--primary) 0%, var(--accent) 100%) 1;
}

[data-theme="dark"] .content-body h3::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 50%;
  height: 2px;
  background: linear-gradient(90deg, var(--primary) 0%, var(--accent) 55%, transparent 100%);
  border-radius: var(--radius-full);
  opacity: 0.4;
}

/* ── h4 — Tertiary headings ── */
.content-body h4 {
  font-family: var(--font-display);
  font-size: clamp(0.95rem, 1.1vw, 1.08rem);
  font-weight: 700;
  color: var(--text-primary);
  margin: 1.4rem 0 .55rem;
  letter-spacing: -0.005em;
  line-height: 1.3;
  display: flex;
  align-items: center;
  gap: 0.55rem;
}

/* Gradient accent bar — vertically centred with the text */
.content-body h4::before {
  content: '';
  flex-shrink: 0;
  width: 3px;
  height: 1.05em;
  border-radius: var(--radius-full);
  background: linear-gradient(180deg, var(--primary) 0%, var(--accent) 100%);
}

/* Light mode h4 — deep gold accent ink, distinguishing the tertiary tier and
   tying it to the brand's blue→gold pairing (matches the gold accent bar). */
[data-theme="light"] .content-body h4 {
  background: linear-gradient(90deg, #075E66 0%, #0A7C86 100%);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  color: #075E66;
}

/* Dark mode h4 — subtle light-blue gradient ink (high contrast) */
[data-theme="dark"] .content-body h4 {
  background: linear-gradient(90deg, #E0F7F9 0%, #36C2CC 100%);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  color: #E0F7F9;
}

/* Outcome codes subtitle (moved below headings) */
.outcome-subtitle {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.65rem;
  font-size: .8rem;
  font-weight: 600;
  margin: 0.5rem 0 1rem 0;
  padding-left: 0;
}

/* Individual outcome badge */
.outcome-badge {
  display: inline-block;
  background: var(--primary);
  color: #ffffff;
  padding: 0.4rem 0.85rem;
  border-radius: var(--radius-full);
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  white-space: nowrap;
  box-shadow: 0 2px 5px rgba(10, 124, 134, 0.22);
  transition: all var(--transition);
}

.outcome-badge:hover {
  box-shadow: 0 4px 10px rgba(10, 124, 134, 0.35);
  transform: translateY(-1px);
}

[data-theme="dark"] .outcome-badge {
  background: linear-gradient(135deg, #0A7C86 0%, #0E9AA7 100%);
  box-shadow: 0 2px 8px rgba(10, 124, 134, 0.35);
}

[data-theme="dark"] .outcome-badge:hover {
  box-shadow: 0 4px 12px rgba(10, 124, 134, 0.5);
}

/* Command verb headings (NESA syllabus directives) */
.content-body h2 em,
.content-body h3 em,
.content-body h4 em {
  font-style: italic;
}

.command-verb {
  font-style: italic;
}

.content-body p {
  color: var(--text-secondary);
  margin-bottom: .75rem;
  line-height: 1.7;
  font-size: .95rem;
}

.content-body ul, .content-body ol {
  color: var(--text-secondary);
  margin: .75rem 0 .75rem 1.5rem;
  font-size: .95rem;
}

.content-body li { margin-bottom: .35rem; line-height: 1.6; }

.content-body strong { color: var(--text-primary); font-weight: 600; }

.content-body a {
  color: var(--primary);
  text-decoration: none;
  border-bottom: 1px solid rgba(10,124,134,.3);
  transition: all var(--transition);
}

.content-body a:hover {
  border-bottom-color: var(--primary);
}

/* ═══════════════════════════════════════════════════════════════
   Callout Boxes — refined card design
   ═══════════════════════════════════════════════════════════════ */

.callout {
  display: block;
  padding: 0.8rem 1.1rem 0.85rem;
  border-radius: var(--radius-md);
  margin: 1.1rem 0;
  border: 1px solid;
  border-left-width: 4px;
  transition: box-shadow 200ms cubic-bezier(.4,0,.2,1), transform 200ms cubic-bezier(.4,0,.2,1);
  position: relative;
  font-size: 0.9rem;
  line-height: 1.6;
}

/* Icon-based callouts keep a compact horizontal layout */
.callout:has(.callout-icon) {
  display: flex;
  flex-direction: row;
  gap: 0.8rem;
  align-items: flex-start;
}

.callout:hover {
  transform: translateX(2px);
  box-shadow: 0 3px 12px rgba(0,0,0,.06);
}

/* ── Light/dark callout base shadows ── */
[data-theme="light"] .callout {
  box-shadow: 0 1px 2px rgba(0,0,0,.03);
}
[data-theme="light"] .callout:hover {
  box-shadow: 0 4px 14px rgba(0,0,0,.06);
}
[data-theme="dark"] .callout:hover {
  box-shadow: 0 4px 14px rgba(0,0,0,.28);
}

/* ── Inline label — leads the first line, no chunky stacked pill ── */
.callout > strong:first-child {
  font-weight: 800;
  letter-spacing: 0.01em;
  margin-right: 0.45rem;
}

.callout-icon {
  font-size: 1.1rem;
  flex-shrink: 0;
  margin-top: .05rem;
}

.callout-content strong {
  display: block;
  font-size: .85rem;
  font-weight: 700;
  margin-bottom: .2rem;
}

.callout-content p, .callout-content ul {
  font-size: .88rem;
  margin-bottom: 0;
  color: inherit;
}

.callout-content ul { margin-top: .25rem; }

/* ── Per-type colours — light mode base (label inherits, just bolder) ── */
.callout.info     { background: rgba(6,182,212,.07);  border-color: rgba(6,182,212,.4);  color: #0B5C72; }
.callout.warning  { background: rgba(245,158,11,.08); border-color: rgba(245,158,11,.42); color: #8a3d0b; }
.callout.danger   { background: rgba(239,68,68,.07);  border-color: rgba(239,68,68,.4);  color: #991B1B; }
.callout.success  { background: rgba(34,197,94,.08);  border-color: rgba(34,197,94,.4);  color: #166534; }
.callout.tip      { background: rgba(34,197,94,.08);  border-color: rgba(34,197,94,.4);  color: #166534; }
.callout.exam-tip { background: rgba(10,124,134,.07);  border-color: rgba(10,124,134,.35); color: #075E66; }
.callout.assessor { background: rgba(10,124,134,.07);  border-color: rgba(10,124,134,.35); color: #075E66; }

/* Key principle — distinct gradient wash + primary label, no clunky top bar */
.callout.key {
  background: linear-gradient(135deg, rgba(10,124,134,.1) 0%, rgba(10,124,134,.035) 100%);
  border-color: rgba(10,124,134,.32);
  border-left-color: var(--primary);
  color: #075E66;
}
.callout.key > strong:first-child { color: var(--primary); }

/* ── Per-type label tints (light) — give the lead word a touch more punch ── */
.callout.info > strong:first-child     { color: #0B5C72; }
.callout.warning > strong:first-child  { color: #b45309; }
.callout.danger > strong:first-child   { color: #b91c1c; }
.callout.success > strong:first-child  { color: #15803d; }
.callout.tip > strong:first-child      { color: #15803d; }
.callout.exam-tip > strong:first-child { color: var(--primary); }
.callout.assessor > strong:first-child { color: var(--primary); }

/* ── Dark mode per-type colours ── */
[data-theme="dark"] .callout.info     { color: #7DD3FC; border-color: rgba(6,182,212,.35); }
[data-theme="dark"] .callout.info > strong:first-child { color: #A5F3FC; }
[data-theme="dark"] .callout.warning  { color: #FCD34D; border-color: rgba(245,158,11,.35); }
[data-theme="dark"] .callout.warning > strong:first-child { color: #fde68a; }
[data-theme="dark"] .callout.danger   { color: #FCA5A5; border-color: rgba(239,68,68,.35); }
[data-theme="dark"] .callout.danger > strong:first-child { color: #fecaca; }
[data-theme="dark"] .callout.success  { color: #86EFAC; border-color: rgba(34,197,94,.35); }
[data-theme="dark"] .callout.success > strong:first-child { color: #bbf7d0; }
[data-theme="dark"] .callout.tip      { color: #86EFAC; border-color: rgba(34,197,94,.35); }
[data-theme="dark"] .callout.tip > strong:first-child { color: #bbf7d0; }
[data-theme="dark"] .callout.exam-tip { color: #B8EDF1; border-color: rgba(54,194,204,.35); }
[data-theme="dark"] .callout.exam-tip > strong:first-child { color: #E0F7F9; }
[data-theme="dark"] .callout.assessor { color: #B8EDF1; border-color: rgba(54,194,204,.35); }
[data-theme="dark"] .callout.assessor > strong:first-child { color: #E0F7F9; }
[data-theme="dark"] .callout.key {
  background: linear-gradient(135deg, rgba(54,194,204,.16) 0%, rgba(10,124,134,.06) 100%);
  border-color: rgba(54,194,204,.4);
  border-left-color: var(--primary);
  color: #B8EDF1;
}
[data-theme="dark"] .callout.key > strong:first-child { color: #B8EDF1; }

/* ── Curriculum Alignment Banners ── */
.curriculum-banner {
  margin-top: 1.5rem;
}
/* Banners keep a distinct badge label (overrides the inline callout label) */
.curriculum-banner > strong:first-child {
  display: inline-block;
  margin: 0 0 0.45rem 0;
  padding: 0.2rem 0.6rem;
  border-radius: var(--radius-sm);
  font-size: 0.7rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}
/* NOTE: .curriculum-banner lives inside .topic-header, which has a dark
   background in BOTH light and dark themes — so the banner always uses
   light text to stay readable (fixes the previous blue-on-dark issue). */
.curriculum-banner.sd {
  background: linear-gradient(135deg, rgba(109,63,217,.18) 0%, rgba(109,63,217,.08) 100%);
  border-left-color: #7DD3FC;
  color: #DDD6FE;                 /* light body text — readable on the dark header */
}
.curriculum-banner.sd strong {
  color: #F5F3FF;                 /* near-white for emphasised terms */
}
.curriculum-banner.sd > strong:first-child {
  background: #6D3FD9;
  color: #fff;                    /* badge label stays white-on-blue */
}
.curriculum-banner.sd a {
  color: #C4B5FD;
  font-weight: 600;
  border-bottom: 1px solid rgba(174,203,251,.45);
}
.curriculum-banner.sd a:hover { border-bottom-color: #C4B5FD; }
.curriculum-banner.eis {
  background: linear-gradient(135deg, rgba(14,116,144,.18) 0%, rgba(14,116,144,.08) 100%);
  border-left-color: #38BDF8;
  color: #CFF3FA;                 /* light body text — readable on the dark header */
}
.curriculum-banner.eis strong {
  color: #ECFBFE;                 /* near-white for emphasised terms */
}
.curriculum-banner.eis > strong:first-child {
  background: #0E7490;
  color: #fff;
}
.curriculum-banner.eis a {
  color: #7DD3FC;
  font-weight: 600;
  border-bottom: 1px solid rgba(143,240,200,.45);
}
.curriculum-banner.eis a:hover { border-bottom-color: #7DD3FC; }
[data-theme="dark"] .curriculum-banner.sd {
  background: linear-gradient(135deg, rgba(109,63,217,.15) 0%, rgba(109,63,217,.06) 100%);
  border-left-color: #7DD3FC;
  color: #DDD6FE;
}
[data-theme="dark"] .curriculum-banner.sd strong {
  color: #EDE9FE;
}
[data-theme="dark"] .curriculum-banner.sd > strong:first-child {
  background: #6D3FD9;
  color: #fff;
}
[data-theme="dark"] .curriculum-banner.sd a {
  color: #C4B5FD;
  border-bottom-color: rgba(147,197,253,.4);
}
[data-theme="dark"] .curriculum-banner.eis {
  background: linear-gradient(135deg, rgba(14,116,144,.15) 0%, rgba(14,116,144,.06) 100%);
  border-left-color: #38BDF8;
  color: #BAE6FD;
}
[data-theme="dark"] .curriculum-banner.eis strong {
  color: #E0F2FE;
}
[data-theme="dark"] .curriculum-banner.eis > strong:first-child {
  background: #0E7490;
  color: #fff;
}
[data-theme="dark"] .curriculum-banner.eis a {
  color: #7DD3FC;
  border-bottom-color: rgba(110,231,183,.4);
}

/* ── Video Resource Boxes ── */
.video-box {
  margin: 1.75rem 0;
  padding: 1.15rem 1.4rem 1.25rem;
  border: 1px solid rgba(220,38,38,.28);
  border-left: 5px solid #DC2626;
  border-radius: var(--radius-lg);
  background: linear-gradient(135deg, rgba(220,38,38,.06) 0%, rgba(220,38,38,.02) 100%);
  transition: all 220ms cubic-bezier(.4,0,.2,1);
}
.video-box:hover {
  box-shadow: 0 6px 18px rgba(220,38,38,.12);
  transform: translateX(2px);
}
.video-box-label {
  display: inline-flex;
  align-items: center;
  gap: .5rem;
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: #B91C1C;
  margin-bottom: .85rem;
}
.video-box-label .video-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 1.4rem;
  height: 1.4rem;
  border-radius: 6px;
  background: #DC2626;
  color: #fff;
  font-size: .7rem;
  padding-left: 2px;
}
.video-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: .55rem;
}
.video-list li {
  margin: 0;
  padding: 0;
}
.video-list a {
  display: flex;
  align-items: baseline;
  gap: .5rem;
  font-weight: 600;
  color: var(--text);
  text-decoration: none;
  line-height: 1.4;
}
.video-list a::before {
  content: "▶";
  color: #DC2626;
  font-size: .7rem;
  flex-shrink: 0;
  transform: translateY(-1px);
}
.video-list a:hover { color: #B91C1C; }
.video-list a:hover .video-meta { color: #B91C1C; }
.video-meta {
  font-weight: 500;
  font-size: .82rem;
  color: var(--text-muted);
}
.video-box-note {
  font-size: .82rem;
  color: var(--text-muted);
  margin: .85rem 0 0;
  font-style: italic;
}
[data-theme="dark"] .video-box {
  border-color: rgba(248,113,113,.28);
  border-left-color: #F87171;
  background: linear-gradient(135deg, rgba(248,113,113,.10) 0%, rgba(248,113,113,.03) 100%);
}
[data-theme="dark"] .video-box-label { color: #FCA5A5; }
[data-theme="dark"] .video-box-label .video-icon { background: #EF4444; }
[data-theme="dark"] .video-list a:hover,
[data-theme="dark"] .video-list a:hover .video-meta { color: #FCA5A5; }
[data-theme="dark"] .video-list a::before { color: #F87171; }

/* ── Code Blocks ── */
.code-block {
  position: relative;
  margin: 1.25rem 0;
}

.code-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: var(--bg-tertiary);
  padding: .6rem 1rem;
  border-radius: var(--radius-lg) var(--radius-lg) 0 0;
  border-bottom: 2px solid var(--border-strong);
}

[data-theme="dark"] .code-header {
  background: #111C2E;
  border-bottom-color: rgba(255,255,255,.15);
}

.code-lang {
  font-size: .72rem;
  font-weight: 700;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: .06em;
}

[data-theme="dark"] .code-lang {
  color: #8FA0B8;
}

.code-dots {
  display: flex;
  gap: .375rem;
}

.code-dots span {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--border-strong);
}

[data-theme="dark"] .code-dots span {
  background: #22324A;
}

/* Light mode code blocks */
pre {
  background: var(--bg-secondary);
  border-radius: 0 0 var(--radius-lg) var(--radius-lg);
  padding: 1.25rem 1.25rem;
  overflow-x: auto;
  margin: 0;
  border: 1px solid var(--border-strong);
  border-top: none;
  box-shadow: var(--shadow-sm);
}

pre code {
  font-family: var(--font-mono);
  font-size: .83rem;
  line-height: 1.7;
  color: var(--text-primary);
}

/* Dark mode code blocks */
[data-theme="dark"] pre {
  background: #0A1220;
  border: 1px solid rgba(255,255,255,.08);
  border-top: none;
}

[data-theme="dark"] pre code {
  color: #E1E9F3;
}

code {
  font-family: var(--font-mono);
  font-size: .85em;
  background: var(--bg-secondary);
  color: var(--primary);
  padding: .15em .4em;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-strong);
}

/* Inline code in dark mode */
[data-theme="dark"] code {
  background: #111C2E;
  color: #7DD3FC;
  border-color: rgba(255,255,255,.18);
}

pre code {
  background: none;
  border: none;
  padding: 0;
  color: inherit;
}

pre.text-diagram {
  font-family: var(--font-mono);
  font-size: .83rem;
  line-height: 1.6;
  padding: 1rem 1.25rem;
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  overflow-x: auto;
  white-space: pre;
}

[data-theme="dark"] pre.text-diagram {
  background: #0A1220;
  border-color: rgba(255,255,255,.08);
  color: #e2e8f0;
}

[data-theme="light"] pre.text-diagram {
  color: #1e293b;
}

/* Syntax colours — Light mode */
.kw  { color: #7C3AED; }  /* keywords */
.fn  { color: #2563EB; }  /* functions */
.str { color: #16A34A; }  /* strings */
.num { color: #D97706; }  /* numbers */
.cm  { color: #6B7280; font-style: italic; }  /* comments */
.cl  { color: #C026D3; }  /* classes */
.op  { color: #5F6E85; }  /* operators */

/* Syntax colours — Dark mode */
[data-theme="dark"] .kw  { color: #7DD3FC; }  /* keywords */
[data-theme="dark"] .fn  { color: #7DD3FC; }  /* functions */
[data-theme="dark"] .str { color: #86EFAC; }  /* strings */
[data-theme="dark"] .num { color: #FDBA74; }  /* numbers */
[data-theme="dark"] .cm  { color: #8797AD; }  /* comments */
[data-theme="dark"] .cl  { color: #F0ABFC; }  /* classes */
[data-theme="dark"] .op  { color: #8FA0B8; }  /* operators */

/* ── Definition Cards ── */
.def-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1rem 1.25rem;
  margin: .75rem 0;
  box-shadow: 0 1px 4px rgba(10,124,134,0.06), 0 1px 2px rgba(0,0,0,0.04);
  transition: box-shadow var(--transition), border-color var(--transition), transform var(--transition);
}

.def-card:hover {
  box-shadow: 0 4px 16px rgba(10,124,134,0.14), 0 2px 6px rgba(0,0,0,0.06);
  border-color: rgba(10,124,134,0.5);
  transform: translateY(-1px);
}

.def-term {
  font-size: .9rem;
  font-weight: 700;
  color: var(--primary);
  margin-bottom: .35rem;
}

.def-meaning {
  font-size: .88rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

/* ── Info Grid ── */
.info-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: 1rem;
  margin: 1.25rem 0;
}

.info-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.25rem;
  transition: box-shadow var(--transition), border-color var(--transition), transform var(--transition);
  box-shadow: 0 1px 4px rgba(10,124,134,0.06), 0 1px 2px rgba(0,0,0,0.04);
}

.info-card:hover {
  box-shadow: 0 4px 16px rgba(10,124,134,0.14), 0 2px 6px rgba(0,0,0,0.06);
  border-color: rgba(10,124,134,0.4);
  transform: translateY(-1px);
}

.info-card-icon {
  font-size: 1.5rem;
  margin-bottom: .75rem;
}

/* Reset h4 dot-accent inside cards and steps */
.info-card h4,
.step-content h4 {
  padding-left: 0;
}

.info-card h4::before,
.step-content h4::before {
  display: none;
}

.info-card h4 {
  font-size: .9rem;
  font-weight: 700;
  margin-bottom: .5rem;
  color: var(--text-primary);
}

.info-card p {
  font-size: .82rem;
  color: var(--text-muted);
  line-height: 1.5;
  margin: 0;
}

/* ── Comparison Tables ── */
.table-wrap {
  overflow-x: auto;
  margin: 1.25rem 0;
  border-radius: var(--radius-lg);
  border: 1px solid var(--border);
  /* Horizontal scroll shadow indicators */
  background:
    linear-gradient(to right, var(--bg) 30%, transparent),
    linear-gradient(to left, var(--bg) 30%, transparent),
    linear-gradient(to right, rgba(0,0,0,.12), transparent 15px),
    linear-gradient(to left, rgba(0,0,0,.12), transparent 15px);
  background-position: left center, right center, left center, right center;
  background-repeat: no-repeat;
  background-size: 20px 100%, 20px 100%, 15px 100%, 15px 100%;
  background-attachment: local, local, scroll, scroll;
}

table {
  width: 100%;
  border-collapse: collapse;
  font-size: .88rem;
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-md);
  overflow: hidden;
}

thead th {
  background: var(--bg-secondary);
  color: var(--text-primary);
  font-weight: 700;
  padding: .75rem 1rem;
  text-align: left;
  border-bottom: 2px solid var(--border-strong);
  white-space: nowrap;
  position: sticky;
  top: 0;
  z-index: 2;
}

tbody td {
  padding: .7rem 1rem;
  color: var(--text-secondary);
  border-bottom: 1px solid var(--border);
  vertical-align: top;
}

tbody tr:nth-child(even) td {
  background: rgba(10, 124, 134, 0.02);
}

tbody tr:hover td {
  background: rgba(10, 124, 134, 0.06);
}

tbody tr:last-child td { border-bottom: none; }

/* ── Key Terms List ── */
.key-terms {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 1rem;
  margin: 1.5rem 0;
}

.key-term-item {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
  padding: 1.125rem 1.25rem;
  border-radius: var(--radius-md);
  border: 1px solid transparent;
  border-bottom: 2px solid var(--border);
  font-size: .85rem;
  line-height: 1.6;
  transition: all var(--transition);
}

.key-term-item:last-child {
  border-bottom: 1px solid transparent;
}

.key-term-item:nth-child(odd) {
  background: var(--primary-light);
  border-color: rgba(10, 124, 134, 0.12);
}

.key-term-item:nth-child(even) {
  background: var(--bg-secondary);
  border-color: var(--border);
}

.key-term-item:hover {
  border-color: var(--primary);
  box-shadow: var(--shadow-sm);
  transform: translateY(-1px);
}

.key-term-item > strong {
  color: var(--text-primary);
  font-weight: 700;
  font-size: 0.9rem;
  line-height: 1.3;
  display: block;
}

.key-term-item > span {
  color: var(--text-secondary);
  font-size: .84rem;
}

/* Dark mode divider styling */
[data-theme="dark"] .key-term-item {
  border-bottom-color: rgba(148, 163, 184, 0.2);
}

/* ── Content Dividers for Structured Lists ── */
.structured-content > h4 {
  margin-top: 1.25rem;
  margin-bottom: 0.75rem;
  padding-bottom: 0.5rem;
  border-bottom: 2px solid var(--border);
}

.structured-content > h4:first-child {
  margin-top: 0;
  border-bottom: none;
}

[data-theme="dark"] .structured-content > h4 {
  border-bottom-color: rgba(148, 163, 184, 0.25);
}

/* ── Definition/Error Type Section Dividers ── */
section h4 {
  margin-top: 1.5rem;
  padding-top: 1rem;
  padding-bottom: 0.5rem;
  border-top: 2px solid var(--border);
}

section h4:first-of-type {
  margin-top: 0;
  border-top: none;
  padding-top: 0;
}

[data-theme="dark"] section h4 {
  border-top-color: rgba(148, 163, 184, 0.25);
}

/* ── Steps / Process ── */
.steps {
  counter-reset: step;
  list-style: none;
  margin: 1rem 0;
  position: relative;
}

.step {
  display: flex;
  gap: 1rem;
  margin-bottom: 1.25rem;
  counter-increment: step;
  position: relative;
}

/* Vertical connecting line between step numbers */
.step:not(:last-child) .step-num::after {
  content: '';
  position: absolute;
  left: 16px;
  top: 36px;
  width: 2px;
  bottom: -1.25rem;
  background: linear-gradient(to bottom, var(--primary), rgba(10,124,134,.15));
  border-radius: 1px;
}

.step-num {
  width: 32px;
  height: 32px;
  background: var(--primary);
  color: white;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: .8rem;
  font-weight: 700;
  flex-shrink: 0;
  position: relative;
  z-index: 1;
  box-shadow: 0 2px 6px rgba(10,124,134,.25);
  transition: all var(--transition);
}

.step:hover .step-num {
  transform: scale(1.08);
  box-shadow: 0 3px 10px rgba(10,124,134,.35);
}

.step-content {
  transition: all var(--transition);
}

.step:hover .step-content {
  transform: translateX(2px);
}

.step-content h4 { margin-top: .1rem; }

/* ── Progress Bar ── */
.progress-section {
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  padding: 1.25rem;
  margin-bottom: 1.5rem;
}

.progress-label {
  display: flex;
  justify-content: space-between;
  font-size: .8rem;
  color: var(--text-muted);
  margin-bottom: .5rem;
}

.progress-bar {
  height: 6px;
  background: var(--border);
  border-radius: var(--radius-full);
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--primary), var(--secondary));
  border-radius: var(--radius-full);
  transition: width .6s ease;
}

/* ── Footer ── */
footer {
  background: var(--nav-bg);
  color: #8FA0B8;
  padding: 3rem 1.5rem 2rem;
  margin-top: 4rem;
  border-top: 1px solid rgba(255,255,255,.06);
}

.footer-inner {
  max-width: 1280px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 2.5rem;
}

.footer-brand {
  display: flex;
  align-items: center;
  gap: .75rem;
  margin-bottom: 1rem;
}

.footer-logo {
  width: 36px;
  height: 36px;
  background: transparent;
  border: 1px solid rgba(255,255,255,.22);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-display);
  font-size: 1rem;
  font-weight: 600;
  color: #F3F6FA;
  letter-spacing: -.05em;
}

.footer-name {
  font-weight: 700;
  color: #E1E9F3;
  font-size: .95rem;
}

.footer-desc {
  font-size: .82rem;
  line-height: 1.6;
  color: #8797AD;
}

.footer-col h4 {
  font-size: .8rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .06em;
  color: #C5D2E2;
  margin-bottom: .75rem;
}

.footer-col a {
  display: block;
  font-size: .82rem;
  color: #8797AD;
  text-decoration: none;
  margin-bottom: .4rem;
  transition: color var(--transition);
}

.footer-col a:hover {
  color: #C5D2E2;
  text-decoration: underline;
  text-underline-offset: 3px;
  text-decoration-color: rgba(203,213,225,.4);
}

.footer-bottom {
  max-width: 1280px;
  margin: 2rem auto 0;
  padding-top: 1.5rem;
  border-top: 1px solid rgba(255,255,255,.06);
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: .78rem;
  color: #5F6E85;
}

/* ── Search ── */
.search-bar {
  position: relative;
  max-width: 520px;
  margin: 0 auto 3.5rem;
}

.search-input {
  width: 100%;
  padding: .75rem 1rem .75rem 3rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-full);
  background: var(--surface);
  color: var(--text-primary);
  font-size: .9rem;
  font-family: var(--font-body);
  outline: none;
  transition: all var(--transition);
  box-shadow: var(--shadow-sm);
}

.search-input:hover {
  border-color: var(--primary);
  box-shadow: 0 2px 8px rgba(10,124,134,.1);
}

.search-input:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(10,124,134,.18), 0 4px 12px rgba(10,124,134,.12);
}

.search-icon {
  position: absolute;
  left: 1rem;
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-muted);
  display: flex;
  align-items: center;
  pointer-events: none;
}

.search-icon svg {
  width: 16px;
  height: 16px;
  stroke: currentColor;
  fill: none;
  stroke-width: 2;
  stroke-linecap: round;
}

/* "/" keyboard hint inside search bar */
.search-kbd {
  position: absolute;
  right: .9rem;
  top: 50%;
  transform: translateY(-50%);
  font-size: .7rem;
  font-weight: 600;
  font-family: var(--font-mono);
  color: var(--text-muted);
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: .1rem .45rem;
  pointer-events: none;
  transition: opacity var(--transition);
}

.search-input:focus ~ .search-kbd { opacity: 0; }

@media (max-width: 768px) {
  .search-kbd { display: none; }
}

/* ── Utility ── */
.section-spacer {
  margin-top: 3.5rem;
  margin-bottom: 1.5rem;
}

.tag {
  display: inline-block;
  padding: .2rem .6rem;
  border-radius: var(--radius-full);
  font-size: .72rem;
  font-weight: 600;
}

.highlight-box {
  background: linear-gradient(135deg, var(--primary-light), rgba(68,88,200,.08));
  border: 1px solid rgba(10,124,134,.2);
  border-radius: var(--radius-xl);
  padding: 1.75rem 2rem;
  margin: 3rem 0 1.5rem 0;
}

[data-theme="dark"] .highlight-box {
  background: linear-gradient(135deg, rgba(10,124,134,.12), rgba(68,88,200,.08));
  border-color: rgba(10,124,134,.25);
}

.divider {
  border: none;
  height: 1px;
  background: linear-gradient(90deg,
    transparent 0%,
    var(--border-strong) 18%,
    var(--border-strong) 82%,
    transparent 100%);
  margin: 2.75rem 0;
}

/* Hide dividers when adjacent sections are collapsed */
section:has(> h2.section-collapsed) + .divider {
  display: none;
}
.divider:has(+ section > h2.section-collapsed) {
  display: none;
}

/* ── Responsive ── */
/* ── Large Tablet & Desktop (1200px+) ── */
@media (min-width: 1200px) {
  .sidebar { display: block; }

  .page-layout {
    grid-template-columns: 260px 1fr;
  }

  .footer-inner {
    grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: 2rem;
  }
}

/* ── Large Tablet (1024px - 1199px) ── */
@media (max-width: 1199px) {
  .page-layout {
    grid-template-columns: 1fr;
  }

  .sidebar { display: none; }

  .footer-inner {
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 1.5rem;
  }
}

/* ── Ultra-Wide Screens (1400px+) ── */
@media (min-width: 1400px) {
  .page-layout {
    gap: 2.5rem;
    padding: 0 2rem;
  }

  .nav-inner {
    padding: 0 2rem;
  }

  .hero {
    padding: clamp(3.5rem, 4.5vw, 4.5rem) 2rem;
  }

  .features-bar {
    padding: clamp(2rem, 3vw, 2.25rem) 2rem;
  }
}

/* ── Tablet Portrait (768px and below) ── */
/* The full navigation bar needs about 820px, so phones in landscape get the hamburger
   menu too, instead of a page that scrolls sideways. Same breakpoint as the SE site. */
@media (max-width: 919px) {
  .nav-links { display: none; }
  .hamburger { display: flex; }
}

@media (max-width: 768px) {

  .hero { padding: 3.5rem 1.25rem; }
  .hero-stats { gap: 2rem; }

  .topics-grid { grid-template-columns: 1fr; gap: 1.25rem; }

  .features-bar { grid-template-columns: 1fr 1fr; gap: 1.25rem; }

  .footer-inner { grid-template-columns: 1fr; }

  .info-grid { grid-template-columns: 1fr; }

  .key-terms {
    grid-template-columns: 1fr;
    gap: 0.875rem;
    margin: 1.25rem 0;
  }

  .key-term-item {
    padding: 0.875rem 1rem;
    font-size: .84rem;
  }

}

@media (max-width: 480px) {
  .hero { padding: 3rem 1rem; margin-bottom: 0.5rem; }
  .hero h1 { font-size: 1.75rem; margin-bottom: 1rem; }
  .hero p { font-size: 1rem; margin-bottom: 2rem; }
  .hero-stats { flex-direction: column; gap: 1.25rem; align-items: center; margin-bottom: 2rem; }
  .features-bar { grid-template-columns: 1fr; gap: 1rem; padding: 2rem 1rem; }
  .hero-cta { flex-direction: column; align-items: stretch; }
  .btn { width: 100%; justify-content: center; }
  .section-header { flex-direction: column; align-items: flex-start; gap: 0.75rem; margin-bottom: 1.5rem; }
}

/* ── Course Tools & Utilities ── */
.badge-all { background: rgba(255, 255, 255, 0.15); color: #E8EEF6; }

.text-muted-dark { color: #8FA0B8; }
.max-w-600 { max-width: 600px; }
.mt-2 { margin-top: .5rem; }
.mt-3 { margin-top: 1rem; }
.fs-sm { font-size: .95rem; }
.lh-base { line-height: 1.6; }

/* ── Mermaid Diagrams ── */
.mermaid {
  display: flex;
  justify-content: center;
  align-items: center;
  background: linear-gradient(135deg, #ffffff 0%, #faf9f6 100%);
  padding: 2.5rem;
  border-radius: var(--radius-lg);
  border: 1.5px solid #e3e0d8;
  overflow-x: auto;
  overflow-y: visible;
  margin: 1.75rem 0;
  min-height: 300px;
  box-shadow: inset 0 1px 3px rgba(0,0,0,0.04), 0 2px 6px rgba(10,124,134,0.08);
  transition: all var(--transition);
}

.mermaid:hover {
  box-shadow: inset 0 1px 3px rgba(0,0,0,0.04), 0 6px 16px rgba(10,124,134,0.14);
  border-color: #c9c5b8;
}

@media (max-width: 768px) {
  .mermaid { padding: 1.5rem 1rem; min-height: 0; }
}

.mermaid svg {
  max-width: 100%;
  height: auto;
  display: block;
}


/* Diagram colours for both themes come from scripts/diagram-theme.js at build time. */

/* ─────────────────────────────────────────────────────────────────────────────────── */
/*  DIAGRAM LIGHTBOX MODAL                                                              */
/* ─────────────────────────────────────────────────────────────────────────────────── */

.lightbox-modal {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: var(--z-modal);
  display: none;
  align-items: center;
  justify-content: center;
  backdrop-filter: blur(8px);
}

.lightbox-modal.active,
.lightbox-modal[aria-hidden="false"] {
  display: flex;
}

.lightbox-overlay {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.7);
  transition: background 300ms ease;
}

.lightbox-container {
  position: relative;
  width: 90vw;
  height: 90vh;
  max-width: 1200px;
  max-height: 900px;
  background: var(--bg);
  border-radius: var(--radius-lg);
  border: 1px solid var(--border);
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
  display: flex;
  flex-direction: column;
  animation: slideUp 300ms cubic-bezier(0.16, 1, 0.3, 1);
  z-index: var(--z-toast);
}

@keyframes slideUp {
  from {
    opacity: 0;
    transform: translateY(40px) scale(0.95);
  }
  to {
    opacity: 1;
    transform: translateY(0) scale(1);
  }
}

.lightbox-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1.5rem;
  border-bottom: 1px solid var(--border);
}

.lightbox-title {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--text-primary);
  margin: 0;
  letter-spacing: -0.5px;
}

.lightbox-close {
  background: none;
  border: none;
  font-size: 1.5rem;
  color: var(--text-muted);
  cursor: pointer;
  padding: 0.5rem;
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-md);
  transition: all var(--transition);
  flex-shrink: 0;
}

.lightbox-close:hover,
.lightbox-close:focus {
  background: var(--surface-hover);
  color: var(--text-primary);
  outline: none;
}

.lightbox-canvas {
  flex: 1;
  overflow: hidden;
  position: relative;
  background: var(--surface);
}

.lightbox-content {
  width: 100%;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: visible; /* canvas handles clipping; visible avoids unwanted scrollbars */
  transform-origin: center center;
  cursor: grab;
  /* No transition on transform — causes laggy pan; controlled per-action instead */
  padding: 2rem;
  will-change: transform;
}

.lightbox-content.panning {
  cursor: grabbing;
}

.lightbox-content > svg,
.lightbox-content > img {
  /* Fit the diagram to the canvas at zoom-level 1, preserving aspect ratio.
     Zoom / pan enlarges via transform on the parent .lightbox-content. */
  max-width: 100%;
  max-height: 100%;
  width: auto;
  height: auto;
  display: block;
  filter: drop-shadow(0 2px 8px rgba(0, 0, 0, 0.1));
}

[data-theme="dark"] .lightbox-content > svg {
  filter: drop-shadow(0 2px 8px rgba(0, 0, 0, 0.3));
}

.lightbox-controls {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 1rem;
  padding: 1rem;
  border-top: 1px solid var(--border);
  background: var(--surface-hover);
  flex-wrap: wrap;
}

.lightbox-btn {
  background: var(--primary);
  color: white;
  border: none;
  width: 40px;
  height: 40px;
  border-radius: var(--radius-md);
  font-size: 1.1rem;
  cursor: pointer;
  transition: all var(--transition);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 600;
  flex-shrink: 0;
}

.lightbox-btn:hover,
.lightbox-btn:focus {
  background: var(--primary-dark);
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(10, 124, 134, 0.3);
  outline: none;
}

.lightbox-btn:active {
  transform: translateY(0);
}

.lightbox-zoom-level {
  min-width: 65px;
  text-align: center;
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--text-primary);
  font-family: var(--font-mono);
  padding: 0.5rem;
}

.lightbox-info {
  padding: 0.875rem 1.5rem;
  text-align: center;
  font-size: 0.85rem;
  color: var(--text-muted);
  border-top: 1px solid var(--border);
  background: var(--bg);
}

.lightbox-info kbd {
  background: var(--surface);
  border: 1px solid var(--border-strong);
  border-radius: 4px;
  padding: 2px 8px;
  font-family: inherit;
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-primary);
  white-space: nowrap;
}

/* Responsive Lightbox */
@media (max-width: 1024px) {
  .lightbox-container {
    width: 95vw;
    height: 95vh;
    max-width: 95vw;
  }
}

@media (max-width: 768px) {
  .lightbox-container {
    width: 95vw;
    height: 95vh;
    max-width: 100%;
    max-height: 100%;
    border-radius: var(--radius-md);
  }

  .lightbox-header {
    padding: 1rem;
  }

  .lightbox-title {
    font-size: 1rem;
  }

  .lightbox-controls {
    gap: 0.5rem;
    padding: 0.75rem;
  }

  .lightbox-btn {
    width: 36px;
    height: 36px;
    font-size: 0.95rem;
  }

  .lightbox-info {
    font-size: 0.75rem;
    padding: 0.625rem 1rem;
  }

  .lightbox-content {
    padding: 1rem;
  }
}

/* Dark mode lightbox adjustments */
[data-theme="dark"] .lightbox-container {
  background: #1d1d25;
  border-color: #22324A;
}

[data-theme="dark"] .lightbox-canvas {
  background: #0A1220;
}

[data-theme="dark"] .lightbox-header,
[data-theme="dark"] .lightbox-info {
  border-color: #22324A;
  background: #1d1d25;
}

[data-theme="dark"] .lightbox-title {
  color: #E8EEF6;
}

[data-theme="dark"] .lightbox-close {
  color: #c9c9d3;
}

[data-theme="dark"] .lightbox-close:hover,
[data-theme="dark"] .lightbox-close:focus {
  background: #22324A;
  color: #E8EEF6;
}

[data-theme="dark"] .lightbox-controls {
  background: #1d1d25;
  border-color: #22324A;
}

[data-theme="dark"] .lightbox-btn {
  background: var(--primary);
}

[data-theme="dark"] .lightbox-btn:hover,
[data-theme="dark"] .lightbox-btn:focus {
  background: var(--primary-dark);
  box-shadow: 0 4px 12px rgba(10, 124, 134, 0.3);
}

[data-theme="dark"] .lightbox-zoom-level {
  color: #E8EEF6;
}

[data-theme="dark"] .lightbox-info {
  background: #1d1d25;
  color: #c9c9d3;
}

[data-theme="dark"] .lightbox-info kbd {
  background: #22324A;
  border-color: #5F6E85;
  color: #E8EEF6;
}

/* ── Scroll-to-Top Button ── */
.scroll-top-btn {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: var(--primary);
  color: #ffffff;
  border: none;
  cursor: pointer;
  box-shadow: 0 4px 14px rgba(10,124,134,.35);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.1rem;
  z-index: var(--z-sticky);
  opacity: 0;
  visibility: hidden;
  transform: translateY(12px);
  transition: opacity 260ms ease, visibility 260ms ease, transform 260ms ease,
              background 200ms ease, box-shadow 200ms ease;
}

.scroll-top-btn.visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.scroll-top-btn:hover {
  background: var(--primary-dark);
  box-shadow: 0 6px 20px rgba(10,124,134,.5);
  transform: translateY(-2px);
}

.scroll-top-btn:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 3px;
}

[data-theme="dark"] .scroll-top-btn {
  background: linear-gradient(135deg, #0A7C86, #0E9AA7);
  box-shadow: 0 4px 14px rgba(10,124,134,.4);
}

/* ── Reduced Motion ── */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}

@media (max-width: 768px) {
  .scroll-top-btn {
    bottom: 1.25rem;
    right: 1.25rem;
    width: 40px;
    height: 40px;
    font-size: 1rem;
  }
}

/* ── Copy Code Button ── */
.copy-btn {
  position: absolute;
  top: 8px;
  right: 10px;
  background: rgba(255,255,255,.08);
  color: #C5D2E2;
  border: 1px solid rgba(255,255,255,.15);
  border-radius: var(--radius-sm);
  padding: 3px 10px;
  font-size: .72rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 200ms ease, color 200ms ease, border-color 200ms ease;
  font-family: inherit;
  z-index: var(--z-raised);
}

.copy-btn:hover {
  background: rgba(255,255,255,.16);
  color: #E8EEF6;
}

.copy-btn.copied {
  background: rgba(14,116,144,.25);
  color: #7DD3FC;
  border-color: rgba(14,116,144,.4);
}

.copy-btn:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 2px;
}

/* ── Fade-in Animation ── */
.fade-in {
  animation: fadeInUp .4s ease forwards;
}

@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(16px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* ── Screen-reader only utility ── */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0,0,0,0);
  white-space: nowrap;
  border: 0;
}

/* ── Search no-results message ── */
.search-no-results {
  grid-column: 1 / -1;
  text-align: center;
  color: var(--text-muted);
  font-size: .95rem;
  padding: 2rem 0;
}

/* ============================================================
   HOME PAGE — REFINED INTERACTIONS
   ============================================================ */

/* ── Feature Bar ── */
.feature-item {
  padding: .75rem 1rem;
  border-radius: var(--radius-lg);
  transition: background var(--transition), transform var(--transition), box-shadow var(--transition);
  cursor: default;
  position: relative;
}
.feature-item:hover {
  background: var(--surface);
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.feature-icon {
  background: var(--surface);
  border: 1px solid var(--border);
  color: var(--primary);
  transition: border-color var(--transition), color var(--transition);
}
.feature-icon svg {
  width: 20px;
  height: 20px;
  stroke: currentColor;
  fill: none;
  stroke-width: 1.75;
  stroke-linecap: round;
  stroke-linejoin: round;
}
.feature-item:hover .feature-icon {
  border-color: var(--primary);
}
[data-theme="dark"] .feature-icon {
  background: var(--bg-tertiary);
}

/* ── Topic Card — cursor spotlight ── */
/* --sx/--sy are set from JS as the pointer moves over the card. */
.topic-card::after {
  content: '';
  position: absolute;
  inset: 0;
  background: radial-gradient(280px circle at var(--sx, 50%) var(--sy, 50%), rgba(10,124,134,.07), transparent 65%);
  opacity: 0;
  transition: opacity 260ms ease;
  pointer-events: none;
}
.topic-card:hover::after {
  opacity: 1;
}
[data-theme="dark"] .topic-card::after {
  background: radial-gradient(280px circle at var(--sx, 50%) var(--sy, 50%), rgba(54,194,204,.08), transparent 65%);
}

/* ── Topic Card — scroll entrance ── */
/* JS sets hidden state via inline style, adds .card-visible to enable the slow entrance
   transition, then removes .card-visible on transitionend — restoring the fast hover
   transition (transition:all var(--transition)) from the base .topic-card rule. */
.topic-card {
  will-change: transform, opacity, box-shadow;
}
.topic-card.card-visible {
  transition: opacity 0.55s ease, transform 0.55s cubic-bezier(.4,0,.2,1);
}

/* ── Topic Card — improved hover glow ── */
.topic-card.sd:hover {
  box-shadow: 0 16px 40px rgba(109,63,217,.28), 0 0 0 1px rgba(109,63,217,.2);
}
.topic-card.eis:hover {
  box-shadow: 0 16px 40px rgba(14,116,144,.28), 0 0 0 1px rgba(14,116,144,.2);
}

/* ── Learning Path Section ── */
.learning-path {
  background: var(--bg-secondary);
  padding: 2.5rem 1.5rem;
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
}
.learning-path-inner {
  max-width: 900px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 2rem;
  flex-wrap: wrap;
}
.path-stage {
  text-align: center;
  flex: 1;
  min-width: 200px;
  padding: 1.5rem;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  position: relative;
  box-shadow: 0 2px 8px rgba(10,124,134,0.06), 0 1px 3px rgba(0,0,0,0.04);
  transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
}
.path-stage:hover {
  transform: translateY(-5px);
  box-shadow: 0 12px 32px rgba(10,124,134,0.15), 0 4px 8px rgba(0,0,0,0.06);
  border-color: var(--primary);
}
.path-stage-eis { border-top: 4px solid var(--eis); }
.path-stage-sd { border-top: 4px solid var(--sd); }

.path-icon {
  font-family: var(--font-display);
  font-size: 1.5rem;
  font-weight: 600;
  width: 52px;
  height: 52px;
  margin: 0 auto 0.85rem;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  border: 1px solid var(--border);
  background: var(--bg-secondary);
  color: var(--text-primary);
  transition: border-color var(--transition), background var(--transition);
}
.path-stage-sd .path-icon { color: var(--sd-dark); }
.path-stage-eis .path-icon { color: var(--eis-dark); }
[data-theme="dark"] .path-stage-sd .path-icon { color: #C4B5FD; }
[data-theme="dark"] .path-stage-eis .path-icon { color: #7DD3FC; }
.path-stage:hover .path-icon {
  border-color: var(--border-strong);
}
.path-title {
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
}
.path-desc {
  font-size: 0.85rem;
  color: var(--text-secondary);
  margin-bottom: 0.75rem;
  line-height: 1.5;
}
.path-count {
  display: inline-block;
  padding: 0.35rem 0.85rem;
  background: var(--primary-light);
  color: var(--primary-dark);
  border-radius: var(--radius-full);
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.05em;
}
/* Year-specific path count colours */
.path-stage-sd .path-count { background: var(--sd-light); color: var(--sd-dark); }
.path-stage-eis .path-count { background: var(--eis-light); color: var(--eis-dark); }
[data-theme="dark"] .path-stage-sd .path-count { background: rgba(109,63,217,.18); color: #C4B5FD; }
[data-theme="dark"] .path-stage-eis .path-count { background: rgba(14,116,144,.15); color: #7DD3FC; }

.path-connector {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 80px;
  font-size: 1.5rem;
  color: var(--text-muted);
  font-weight: 400;
}

@media (max-width: 640px) {
  .learning-path { padding: 2rem 1rem; }
  .learning-path-inner { gap: 1rem; flex-direction: column; }
  /* Use individual `rotate` property — doesn't conflict with the translateX in arrow-pulse */
  .path-connector { min-height: 40px; font-size: 1.5rem; rotate: 90deg; animation: none; }
}

/* ── Section Header — accent line ── */
.section-header {
  position: relative;
}
.section-header::after {
  content: '';
  position: absolute;
  left: 0; bottom: -1px;
  width: 56px; height: 2px;
  background: var(--primary);
}

/* Topic count label (replaces inline style) */
.topic-count {
  font-size: .82rem;
  color: var(--text-muted);
  font-weight: 500;
}

/* ── Study Guide Section ── */
.study-guide-section {
  margin-top: 3.5rem;
  padding: 2.5rem 0;
  border-top: 1px solid var(--border);
}
.study-guide-header {
  text-align: center;
  margin-bottom: 2rem;
}
.study-guide-title {
  font-family: var(--font-display);
  font-size: 1.45rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: .4rem;
}
.study-guide-subtitle {
  font-size: .88rem;
  color: var(--text-muted);
}
.study-guide-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1.25rem;
}
.study-guide-card {
  position: relative;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  padding: 1.75rem 1.5rem 1.5rem;
  overflow: clip;   /* clip avoids corner-cropping during hover transform */
  box-shadow: 0 1px 4px rgba(10,124,134,0.06), 0 1px 2px rgba(0,0,0,0.04);
  transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
}
.study-guide-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 12px 32px rgba(10,124,134,0.14), 0 4px 8px rgba(0,0,0,0.06);
  border-color: rgba(10,124,134,0.45);
}
.study-guide-step {
  position: absolute;
  top: 1.25rem; right: 1.25rem;
  font-size: 2.5rem;
  font-weight: 900;
  line-height: 1;
  color: var(--border);
  letter-spacing: -.04em;
  pointer-events: none;
  transition: color var(--transition);
}
.study-guide-card:hover .study-guide-step {
  color: var(--border-strong);
}
.study-guide-icon-wrap {
  width: 44px; height: 44px;
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 1rem;
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  color: var(--primary);
  transition: border-color var(--transition);
}
.study-guide-icon-wrap svg {
  width: 19px;
  height: 19px;
  stroke: currentColor;
  fill: none;
  stroke-width: 1.75;
  stroke-linecap: round;
  stroke-linejoin: round;
}
.study-guide-card:hover .study-guide-icon-wrap {
  border-color: var(--primary);
}

.study-guide-card h3 {
  font-size: .98rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: .5rem;
}
.study-guide-card p {
  font-size: .85rem;
  color: var(--text-secondary);
  line-height: 1.6;
  margin: 0;
}

/* ── Reduced Motion: disable animations ── */
@media (prefers-reduced-motion: reduce) {
  .topic-card,
  .nav-dropdown-menu {
    animation: none !important;
  }
  .path-stage:hover,
  .feature-item:hover,
  .topic-card:hover,
  .study-guide-card:hover,
  .nav-brand:hover .nav-logo,
  .nav-dropdown-menu a:hover {
    transform: none !important;
  }
}

/* ── Print: hide decorative new elements ── */
@media print {
  .study-guide-section, .learning-path { display: none !important; }
}

/* ── Print Styles ── */
@media print {
  /* Hide non-content UI */
  .navbar,
  .mobile-menu,
  .sidebar,
  .scroll-top-btn,
  .reading-progress,
  .copy-btn,
  .lightbox-modal,
  #theme-toggle,
  #theme-toggle-mobile {
    display: none !important;
  }

  /* Full-width single-column layout */
  .page-layout {
    display: block;
  }

  .page-content {
    max-width: 100%;
    padding: 0;
  }

  /* Expand all collapsed sections */
  .section-body.section-collapsed,
  .part-group.part-collapsed {
    grid-template-rows: 1fr !important;
    max-height: none !important;
    display: block !important;
  }

  .section-body-inner {
    overflow: visible !important;
  }

  /* Avoid page breaks inside cards, code blocks and diagrams */
  .topic-card,
  .info-card,
  .def-card,
  .callout,
  .code-block,
  .table-wrap,
  .mermaid,
  .video-box {
    break-inside: avoid;
    page-break-inside: avoid;
  }

  /* Ensure headings don't orphan at bottom of page */
  h2, h3, h4 {
    break-after: avoid;
    page-break-after: avoid;
  }

  /* Reset colors for printing */
  body {
    color: #000 !important;
    background: #fff !important;
  }

  a[href]::after {
    content: ' (' attr(href) ')';
    font-size: .75em;
    color: #555;
  }

  /* Don't print hash anchors */
  a[href^="#"]::after {
    content: none;
  }
}

/* ── Automated Glossary Auto-Links ── */
.glossary-link {
  text-decoration: none;
  font-weight: 600;
  color: var(--primary);
  border-bottom: 1.5px dashed var(--primary);
  padding-bottom: 0.1em;
  transition: all var(--transition);
  position: relative;
  cursor: help;
}
.glossary-link:hover {
  background-color: var(--primary-light);
  border-bottom-style: solid;
}
[data-theme="dark"] .glossary-link:hover {
  background-color: rgba(10, 124, 134, 0.15);
}

/* Safety net: never let an auto-injected glossary link tint heading text or
   text inside coloured banners (prevents blue-on-blue / unreadable links). */
.content-body h1 .glossary-link,
.content-body h2 .glossary-link,
.content-body h3 .glossary-link,
.content-body h4 .glossary-link,
.content-body h5 .glossary-link,
.content-body h6 .glossary-link,
.part-block .glossary-link,
.curriculum-banner .glossary-link,
.syllabus-phase .glossary-link,
.outcome-subtitle .glossary-link,
.syllabus-concept .glossary-link {
  color: inherit;
  border-bottom-color: currentColor;
  opacity: 0.95;
}

/* ============================================================
   DESIGN REFRESH — dark-mode solids, selection, micro-polish
   ============================================================ */

/* Dark mode swaps --primary to a light periwinkle for text/links.
   Elements that pair white text with a primary fill need a deep
   solid instead. */
[data-theme="dark"] .step-num,
[data-theme="dark"] .lightbox-btn {
  background: #0A7C86;
  color: #FFFFFF;
}

[data-theme="dark"] .lightbox-btn:hover,
[data-theme="dark"] .lightbox-btn:focus {
  background: #0A7C86;
}

[data-theme="dark"] .content-body h2.syllabus-phase {
  background: linear-gradient(135deg, #075E66 0%, #0A7C86 100%);
}

[data-theme="dark"] .part-block {
  background: linear-gradient(135deg, #0B1B2E 0%, #075E66 100%);
}

[data-theme="dark"] .outcome-badge {
  background: linear-gradient(135deg, #0A7C86 0%, #0E9AA7 100%);
}

/* Text selection in brand colours */
::selection {
  background: rgba(10,124,134,.16);
  color: inherit;
}
[data-theme="dark"] ::selection {
  background: rgba(54,194,204,.28);
}

/* Footer wordmark matches the serif monogram */
.footer-name,
.nav-title {
  font-family: var(--font-display);
  letter-spacing: .01em;
}

/* Hero CTA quiet secondary link arrow */
.btn-outline .btn-arrow {
  display: inline-block;
  transition: transform var(--transition);
}
.btn-outline:hover .btn-arrow { transform: translateX(3px); }

/* Reveal-on-scroll utility (applied from JS; safe without JS) */
.reveal-item {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity .6s ease, transform .6s cubic-bezier(.22,.61,.36,1);
}
.reveal-item.revealed {
  opacity: 1;
  transform: none;
}
@media (prefers-reduced-motion: reduce) {
  .reveal-item { opacity: 1; transform: none; transition: none; }
}

/* ══════════════════════════════════════════════════════════════
   Mobile Table of Contents — floating button + bottom sheet.
   Phones/tablets only; the left sidebar handles this on desktop.
   ══════════════════════════════════════════════════════════════ */
.mobile-toc-fab { display: none; }

@media (max-width: 768px) {
  .mobile-toc-fab {
    position: fixed;
    bottom: 2rem;
    left: 1.25rem;
    z-index: var(--z-sticky);
    display: inline-flex;
    align-items: center;
    gap: 0.45rem;
    padding: 0.6rem 0.95rem 0.6rem 0.8rem;
    border: none;
    border-radius: var(--radius-full);
    background: var(--primary);
    color: #fff;
    font-family: var(--font-body);
    font-size: 0.82rem;
    font-weight: 600;
    cursor: pointer;
    box-shadow: 0 4px 14px rgba(10,124,134,.35);
    transition: transform 200ms ease, box-shadow 200ms ease, background 200ms ease;
  }
  .mobile-toc-fab svg { width: 18px; height: 18px; flex-shrink: 0; }
  .mobile-toc-fab:active { transform: scale(0.96); }
  .mobile-toc-fab.is-over-footer { opacity: 0; transform: translateY(10px); pointer-events: none; transition: opacity 160ms ease, transform 200ms ease; }
}

[data-theme="dark"] .mobile-toc-fab {
  background: linear-gradient(135deg, #0A7C86, #0E9AA7);
}

.mobile-toc-backdrop {
  position: fixed;
  inset: 0;
  background: rgba(10, 10, 16, 0.5);
  -webkit-backdrop-filter: blur(2px);
  backdrop-filter: blur(2px);
  opacity: 0;
  visibility: hidden;
  transition: opacity 240ms ease, visibility 240ms ease;
  z-index: var(--z-modal);
}
.mobile-toc-backdrop.open { opacity: 1; visibility: visible; }

.mobile-toc-panel {
  position: fixed;
  left: 0;
  right: 0;
  bottom: 0;
  max-height: 72vh;
  display: flex;
  flex-direction: column;
  background: var(--surface);
  border-top-left-radius: var(--radius-2xl);
  border-top-right-radius: var(--radius-2xl);
  box-shadow: 0 -8px 30px rgba(0, 0, 0, 0.25);
  transform: translateY(100%);
  transition: transform 320ms cubic-bezier(.4, 0, .2, 1);
  z-index: var(--z-modal);
}
.mobile-toc-panel.open { transform: translateY(0); }

.mobile-toc-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem 1.25rem 0.8rem;
  border-bottom: 1px solid var(--border);
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 1rem;
  color: var(--text-primary);
  flex-shrink: 0;
}
.mobile-toc-close {
  background: none;
  border: none;
  cursor: pointer;
  font-size: 1.7rem;
  line-height: 1;
  color: var(--text-muted);
  padding: 0 0.25rem;
}
.mobile-toc-close:active { color: var(--text-primary); }

.mobile-toc-list {
  list-style: none;
  margin: 0;
  padding: 0.5rem 0.75rem calc(1.25rem + env(safe-area-inset-bottom, 0px));
  overflow-y: auto;
  -webkit-overflow-scrolling: touch;
}
.mobile-toc-list li { margin: 0; }
.mobile-toc-list .sidebar-label {
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .06em;
  color: var(--primary);
  padding: 0.9rem 0.75rem 0.35rem;
}
[data-theme="dark"] .mobile-toc-list .sidebar-label { color: var(--accent); }
.mobile-toc-list a {
  display: block;
  padding: 0.62rem 0.75rem;
  color: var(--text-secondary);
  text-decoration: none;
  border-radius: var(--radius-md);
  font-size: 0.92rem;
  line-height: 1.35;
  transition: background 160ms ease, color 160ms ease;
}
.mobile-toc-list a:active,
.mobile-toc-list a:hover {
  background: var(--surface-hover);
  color: var(--text-primary);
}
.mobile-toc-list a.active {
  background: var(--primary-light);
  color: var(--primary);
  font-weight: 600;
}
[data-theme="dark"] .mobile-toc-list a.active {
  background: rgba(54, 194, 204, 0.15);
  color: var(--primary);
}

/* Desktop never shows the sheet — the sidebar covers it */
@media (min-width: 769px) {
  .mobile-toc-backdrop,
  .mobile-toc-panel { display: none !important; }
}

/* Respect reduced-motion */
@media (prefers-reduced-motion: reduce) {
  .mobile-toc-panel { transition: none; }
}

/* Keep the floating Contents button clear of the scroll-top button row */
@media print {
  .mobile-toc-fab,
  .mobile-toc-backdrop,
  .mobile-toc-panel { display: none !important; }
}

/* ══════════════════════════════════════════════════════════════
   Copy-link anchors on sub-headings — hover-reveal "share" affordance
   ══════════════════════════════════════════════════════════════ */
.heading-anchor {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 1.15em;
  height: 1.15em;
  margin-left: 0.45rem;
  vertical-align: -0.18em;
  color: var(--primary);
  border: none;
  border-radius: var(--radius-sm);
  text-decoration: none;
  opacity: 0;
  position: relative;
  cursor: pointer;
  transition: opacity 160ms ease, background 160ms ease, color 160ms ease;
  -webkit-text-fill-color: currentColor;   /* override h-heading gradient clip */
}
.heading-anchor svg { width: 0.85em; height: 0.85em; display: block; }

/* Reveal on heading hover, or when the anchor itself is focused */
.content-body h3:hover .heading-anchor { opacity: 0.55; }
.heading-anchor:hover { opacity: 1; background: var(--primary-light); }
.heading-anchor:focus-visible {
  opacity: 1;
  outline: 2px solid var(--primary);
  outline-offset: 2px;
}
[data-theme="dark"] .heading-anchor:hover { background: rgba(54, 194, 204, 0.16); }

/* Touch devices can't hover — keep it gently visible */
@media (pointer: coarse) {
  .heading-anchor { opacity: 0.4; }
}

/* "Copied!" confirmation tooltip */
.heading-anchor.copied { opacity: 1; color: var(--success); }
.heading-anchor.copied::after {
  content: 'Link copied';
  position: absolute;
  left: 50%;
  bottom: 150%;
  transform: translateX(-50%);
  background: var(--text-primary);
  color: var(--bg);
  font-family: var(--font-body);
  font-size: 0.68rem;
  font-weight: 600;
  letter-spacing: 0;
  padding: 0.22rem 0.5rem;
  border-radius: var(--radius-sm);
  white-space: nowrap;
  pointer-events: none;
  box-shadow: var(--shadow-md);
}

@media print {
  .heading-anchor { display: none !important; }
}

/* ══════════════════════════════════════════════════════════════
   View Transitions (progressive enhancement — ignored where unsupported)
   ══════════════════════════════════════════════════════════════ */

/* Smooth cross-fade between same-origin pages */
@view-transition { navigation: auto; }

/* Theme switch: circular reveal of the new theme from the toggle button.
   Scoped to .theme-transition so page-navigation transitions stay a clean fade. */
html.theme-transition::view-transition-old(root),
html.theme-transition::view-transition-new(root) {
  animation: none;
  mix-blend-mode: normal;
}
html.theme-transition::view-transition-old(root) { z-index: 0; }
html.theme-transition::view-transition-new(root) {
  z-index: 1;
  animation: theme-reveal 0.45s cubic-bezier(0.4, 0, 0.2, 1);
}
@keyframes theme-reveal {
  from { clip-path: circle(0 at var(--theme-x, 50%) var(--theme-y, 50%)); }
  to   { clip-path: circle(var(--theme-r, 150%) at var(--theme-x, 50%) var(--theme-y, 50%)); }
}

/* Never animate transitions for reduced-motion users */
@media (prefers-reduced-motion: reduce) {
  ::view-transition-group(*),
  ::view-transition-old(*),
  ::view-transition-new(*) {
    animation: none !important;
  }
}

/* ── Topic and part intros (themed in theme.css) ── */
.topic-breakout { margin: 0 0 2rem; }
.topic-breakout p { margin: 0 0 .7rem; line-height: 1.7; }
.topic-breakout p:last-child { margin-bottom: 0; }
.topic-breakout .breakout-question { font-style: italic; }
.topic-breakout .bq-lead { display: block; font-style: normal; font-size: .72rem; font-weight: 800; letter-spacing: .1em; text-transform: uppercase; }
.visually-hidden { position: absolute !important; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }