/* ==========================================================================
   ASI-2026: SUPERINTELLIGENCE 10-HOUR COURSE PORTAL — SWISS ACADEMIC REDESIGN
   Multilingual Typography (CJK · Latin · Cyrillic) + Precision Grid Architecture
   ========================================================================== */

:root {
  /* Light Mode: Warm Archival Ivory & Swiss Ink */
  --bg-canvas: #f8f7f3;
  --bg-surface: #ffffff;
  --bg-elevated: #f1efe8;
  --bg-subtle: #e7e4da;
  --bg-glass: rgba(248, 247, 243, 0.88);
  --bg-hero-grid: radial-gradient(rgba(18, 20, 26, 0.07) 1px, transparent 1px);

  --ink-primary: #0f1117;
  --ink-body: #252830;
  --ink-secondary: #4e5360;
  --ink-muted: #747a88;

  --border-hairline: #dfdcd2;
  --border-strong: #c2bdb0;
  --border-focus: #1d4ed8;

  /* Four Module Semantic Palette */
  --mod-1-color: #1d4ed8;
  --mod-1-bg: #dbeafe;
  --mod-1-border: #93c5fd;

  --mod-2-color: #047857;
  --mod-2-bg: #d1fae5;
  --mod-2-border: #6ee7b7;

  --mod-3-color: #b45309;
  --mod-3-bg: #fef3c7;
  --mod-3-border: #fcd34d;

  --mod-4-color: #be123c;
  --mod-4-bg: #ffe4e6;
  --mod-4-border: #fda4af;

  /* Multilingual Font Stacks (Optimized for ZH, EN, DE, FR, RU) */
  --font-serif: "Charter", "Iowan Old Style", "Newsreader", "Source Serif 4", "PT Serif", "Noto Serif SC", Georgia, serif;
  --font-sans: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", "PingFang SC", "Noto Sans", "Noto Sans CJK SC", sans-serif;
  --font-mono: "JetBrains Mono", "SFMono-Regular", "Fira Code", Menlo, Consolas, monospace;

  --shadow-xs: 0 1px 2px rgba(15, 17, 23, 0.04);
  --shadow-sm: 0 2px 10px rgba(15, 17, 23, 0.05), 0 1px 2px rgba(15, 17, 23, 0.04);
  --shadow-md: 0 10px 28px rgba(15, 17, 23, 0.07), 0 2px 6px rgba(15, 17, 23, 0.04);
  --shadow-lg: 0 24px 56px rgba(15, 17, 23, 0.16), 0 4px 14px rgba(15, 17, 23, 0.08);

  --radius-xs: 4px;
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 14px;
}

[data-theme="dark"] {
  --bg-canvas: #090c12;
  --bg-surface: #101520;
  --bg-elevated: #161d2b;
  --bg-subtle: #1e2738;
  --bg-glass: rgba(9, 12, 18, 0.88);
  --bg-hero-grid: radial-gradient(rgba(148, 163, 184, 0.11) 1px, transparent 1px);

  --ink-primary: #f1f5f9;
  --ink-body: #cbd5e1;
  --ink-secondary: #94a3b8;
  --ink-muted: #64748b;

  --border-hairline: #1e293b;
  --border-strong: #334155;
  --border-focus: #60a5fa;

  --mod-1-color: #60a5fa;
  --mod-1-bg: rgba(37, 99, 235, 0.15);
  --mod-1-border: rgba(96, 165, 250, 0.36);

  --mod-2-color: #34d399;
  --mod-2-bg: rgba(5, 150, 105, 0.15);
  --mod-2-border: rgba(52, 211, 153, 0.36);

  --mod-3-color: #fbbf24;
  --mod-3-bg: rgba(217, 119, 6, 0.15);
  --mod-3-border: rgba(251, 191, 36, 0.36);

  --mod-4-color: #fb7185;
  --mod-4-bg: rgba(225, 29, 72, 0.15);
  --mod-4-border: rgba(251, 113, 133, 0.36);

  --shadow-xs: 0 1px 2px rgba(0, 0, 0, 0.35);
  --shadow-sm: 0 4px 12px rgba(0, 0, 0, 0.4);
  --shadow-md: 0 12px 32px rgba(0, 0, 0, 0.55);
  --shadow-lg: 0 28px 64px rgba(0, 0, 0, 0.72);
}

*, *::before, *::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
  scrollbar-gutter: stable;
}

body {
  margin: 0;
  background-color: var(--bg-canvas);
  color: var(--ink-body);
  font-family: var(--font-sans);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  transition: background-color 0.2s ease, color 0.2s ease;
}

/* Below-the-fold rendering optimization (defer-rendering-heavy-content) */
.heavy-section-deferred {
  content-visibility: auto;
  contain-intrinsic-size: auto none auto 620px;
}

/* ==========================================================================
   1. STICKY COMMAND NAVIGATION BAR & 5-LANGUAGE SEGMENTED SWITCHER
   ========================================================================== */
.site-nav {
  position: sticky;
  top: 0;
  z-index: 120;
  background: var(--bg-glass);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--border-hairline);
}

.site-nav-inner {
  max-width: 1440px;
  margin: 0 auto;
  padding: 0.6rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.85rem;
  flex-wrap: wrap;
}

.brand-cluster {
  display: flex;
  align-items: center;
  gap: 0.65rem;
}

.brand-seal {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0.24rem 0.58rem;
  background: var(--ink-primary);
  color: var(--bg-canvas);
  font-family: var(--font-mono);
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  border-radius: var(--radius-xs);
}

.brand-title {
  font-weight: 700;
  font-size: 0.88rem;
  color: var(--ink-primary);
  letter-spacing: -0.01em;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 1.1rem;
  flex-wrap: wrap;
}

.nav-links a {
  color: var(--ink-secondary);
  text-decoration: none;
  font-size: 0.8rem;
  font-weight: 600;
  transition: color 0.15s ease;
}

.nav-links a:hover {
  color: var(--mod-1-color);
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 0.55rem;
  flex-wrap: wrap;
}

/* 5-Language Segmented Pill Switcher */
.lang-switcher {
  display: inline-flex;
  align-items: center;
  background: var(--bg-elevated);
  border: 1px solid var(--border-strong);
  border-radius: 999px;
  padding: 0.16rem;
  gap: 0.12rem;
}

.lang-btn {
  border: none;
  background: transparent;
  color: var(--ink-secondary);
  font-family: var(--font-mono);
  font-size: 0.72rem;
  font-weight: 700;
  padding: 0.24rem 0.58rem;
  border-radius: 999px;
  cursor: pointer;
  transition: all 0.15s ease;
  line-height: 1.2;
}

.lang-btn:hover {
  color: var(--ink-primary);
}

.lang-btn[aria-pressed="true"] {
  background: var(--ink-primary);
  color: var(--bg-canvas);
  box-shadow: var(--shadow-xs);
}

.progress-pill {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  padding: 0.26rem 0.65rem;
  background: var(--bg-elevated);
  border: 1px solid var(--border-hairline);
  border-radius: 999px;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--ink-secondary);
}

.progress-bar-mini {
  width: 48px;
  height: 6px;
  background: var(--border-hairline);
  border-radius: 999px;
  overflow: hidden;
}

.progress-bar-fill {
  height: 100%;
  background: var(--mod-2-color);
  width: 0%;
  transition: width 0.3s ease;
}

.btn-outline, .btn-primary {
  display: inline-flex;
  align-items: center;
  gap: 0.38rem;
  padding: 0.36rem 0.76rem;
  font-family: var(--font-sans);
  font-size: 0.78rem;
  font-weight: 600;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all 0.15s ease;
  text-decoration: none;
}

.btn-outline {
  background: var(--bg-surface);
  color: var(--ink-primary);
  border: 1px solid var(--border-strong);
}

.btn-outline:hover {
  background: var(--bg-elevated);
  border-color: var(--ink-secondary);
}

.btn-primary {
  background: var(--mod-1-color);
  color: #ffffff;
  border: 1px solid transparent;
}

.btn-primary:hover {
  filter: brightness(1.08);
}

/* ==========================================================================
   2. ARCHITECTURAL HERO SECTION & FORMAL AXIOM PANEL
   ========================================================================== */
.hero-header {
  position: relative;
  border-bottom: 1px solid var(--border-hairline);
  padding: 3.25rem 1.5rem 2.75rem;
  background-color: var(--bg-canvas);
  background-image:
    radial-gradient(circle at 86% 14%, var(--mod-1-bg), transparent 36%),
    radial-gradient(circle at 10% 88%, var(--mod-2-bg), transparent 32%),
    var(--bg-hero-grid);
  background-size: 100% 100%, 100% 100%, 22px 22px;
}

.hero-container {
  max-width: 1440px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: 1.38fr 1fr;
  gap: 2.5rem;
  align-items: stretch;
}

.hero-main-col {
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.hero-kicker-row {
  display: flex;
  align-items: center;
  gap: 0.55rem;
  flex-wrap: wrap;
  margin-bottom: 1rem;
}

.hero-kicker {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.07em;
  text-transform: uppercase;
  color: var(--mod-1-color);
  background: var(--mod-1-bg);
  border: 1px solid var(--mod-1-border);
  padding: 0.25rem 0.65rem;
  border-radius: 999px;
}

.hero-lang-badge {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--ink-muted);
  background: var(--bg-surface);
  border: 1px solid var(--border-hairline);
  padding: 0.22rem 0.55rem;
  border-radius: 999px;
}

.hero-title {
  font-family: var(--font-serif);
  font-size: clamp(2rem, 3.2vw, 2.95rem);
  line-height: 1.18;
  font-weight: 700;
  color: var(--ink-primary);
  margin: 0 0 1rem;
  letter-spacing: -0.02em;
}

.hero-subtitle {
  font-family: var(--font-serif);
  font-size: 1.08rem;
  line-height: 1.68;
  color: var(--ink-secondary);
  margin: 0 0 1.6rem;
  max-width: 70ch;
}

.hero-cta-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.7rem;
  align-items: center;
  margin-bottom: 1.75rem;
}

/* Swiss Metric Ribbon inside Hero Left */
.hero-metrics-ribbon {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-md);
  background: var(--bg-surface);
  overflow: hidden;
  box-shadow: var(--shadow-xs);
}

.ribbon-cell {
  padding: 0.75rem 0.9rem;
  border-right: 1px solid var(--border-hairline);
}

.ribbon-cell:last-child {
  border-right: none;
}

.ribbon-num {
  display: block;
  font-family: var(--font-mono);
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--ink-primary);
}

.ribbon-label {
  font-size: 0.72rem;
  color: var(--ink-muted);
  font-weight: 500;
}

/* Hero Right: Formal Mathematical Spine Card */
.hero-axiom-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-strong);
  border-top: 4px solid var(--mod-1-color);
  border-radius: var(--radius-md);
  padding: 1.35rem 1.45rem;
  box-shadow: var(--shadow-md);
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.axiom-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 0.8rem;
  padding-bottom: 0.55rem;
  border-bottom: 1px solid var(--border-hairline);
}

.axiom-title {
  font-family: var(--font-mono);
  font-size: 0.73rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--ink-secondary);
}

.axiom-tag {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  padding: 0.14rem 0.45rem;
  background: var(--bg-elevated);
  border-radius: var(--radius-xs);
  color: var(--mod-1-color);
  font-weight: 600;
}

.axiom-eq-box {
  background: var(--bg-elevated);
  border: 1px solid var(--border-hairline);
  border-left: 3px solid var(--mod-1-color);
  border-radius: var(--radius-sm);
  padding: 0.68rem 0.85rem;
  margin-bottom: 0.68rem;
  overflow-x: auto;
  font-size: 0.85rem;
}

.axiom-eq-box:nth-of-type(2) {
  border-left-color: var(--mod-3-color);
}

.axiom-eq-box:nth-of-type(3) {
  border-left-color: var(--mod-2-color);
  margin-bottom: 0;
}

.axiom-eq-label {
  font-family: var(--font-mono);
  font-size: 0.69rem;
  font-weight: 600;
  color: var(--ink-secondary);
  margin-bottom: 0.22rem;
  display: block;
}

/* Metadata Strip */
.meta-strip {
  background: var(--bg-surface);
  border-bottom: 1px solid var(--border-hairline);
  padding: 0.9rem 1.5rem;
}

.meta-strip-inner {
  max-width: 1440px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1.25rem;
}

.meta-item {
  border-left: 2px solid var(--mod-1-color);
  padding-left: 0.85rem;
}

.meta-item:nth-child(2) { border-left-color: var(--mod-2-color); }
.meta-item:nth-child(3) { border-left-color: var(--mod-3-color); }
.meta-item:nth-child(4) { border-left-color: var(--mod-4-color); }

.meta-item-label {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--ink-muted);
  margin-bottom: 0.14rem;
}

.meta-item-value {
  font-size: 0.83rem;
  font-weight: 600;
  color: var(--ink-primary);
}

/* ==========================================================================
   3. MAIN CONTAINER & SECTION HEADERS
   ========================================================================== */
.main-container {
  max-width: 1440px;
  margin: 0 auto;
  padding: 2.75rem 1.5rem 4.5rem;
}

.section-block {
  margin-bottom: 4.25rem;
}

.section-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
  gap: 1rem;
  flex-wrap: wrap;
  margin-bottom: 1.6rem;
  padding-bottom: 0.85rem;
  border-bottom: 2px solid var(--ink-primary);
}

.section-kicker {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--mod-1-color);
  margin-bottom: 0.25rem;
}

.section-title {
  font-family: var(--font-serif);
  font-size: 1.72rem;
  font-weight: 700;
  color: var(--ink-primary);
  margin: 0;
}

.section-desc {
  font-size: 0.9rem;
  color: var(--ink-secondary);
  max-width: 72ch;
  margin: 0.35rem 0 0;
}

/* ==========================================================================
   4. BENTO 4-MODULE ARCHITECTURE GRID
   ========================================================================== */
.module-pillars-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1.15rem;
}

.module-pillar-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-hairline);
  border-radius: var(--radius-md);
  padding: 1.3rem;
  box-shadow: var(--shadow-xs);
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  transition: transform 0.16s ease, box-shadow 0.16s ease, border-color 0.16s ease;
  cursor: pointer;
}

.module-pillar-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
  border-color: var(--border-strong);
}

.module-pillar-card[data-mod="1"] { border-top: 4px solid var(--mod-1-color); }
.module-pillar-card[data-mod="2"] { border-top: 4px solid var(--mod-2-color); }
.module-pillar-card[data-mod="3"] { border-top: 4px solid var(--mod-3-color); }
.module-pillar-card[data-mod="4"] { border-top: 4px solid var(--mod-4-color); }

.mod-pill {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.69rem;
  font-weight: 700;
  padding: 0.18rem 0.52rem;
  border-radius: var(--radius-xs);
  margin-bottom: 0.65rem;
}

.mod-pill-1 { background: var(--mod-1-bg); color: var(--mod-1-color); border: 1px solid var(--mod-1-border); }
.mod-pill-2 { background: var(--mod-2-bg); color: var(--mod-2-color); border: 1px solid var(--mod-2-border); }
.mod-pill-3 { background: var(--mod-3-bg); color: var(--mod-3-color); border: 1px solid var(--mod-3-border); }
.mod-pill-4 { background: var(--mod-4-bg); color: var(--mod-4-color); border: 1px solid var(--mod-4-border); }

.mod-card-title {
  font-family: var(--font-serif);
  font-size: 1.14rem;
  font-weight: 700;
  color: var(--ink-primary);
  margin: 0 0 0.45rem;
}

.mod-card-summary {
  font-size: 0.82rem;
  color: var(--ink-secondary);
  margin: 0 0 0.95rem;
}

.mod-lecture-mini-list {
  list-style: none;
  padding: 0.7rem 0 0;
  margin: 0;
  border-top: 1px dashed var(--border-hairline);
  font-size: 0.78rem;
}

.mod-lecture-mini-list li {
  padding: 0.24rem 0;
  color: var(--ink-body);
  display: flex;
  gap: 0.45rem;
  align-items: baseline;
}

.mod-lecture-mini-list span.l-num {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  font-weight: 700;
  color: var(--ink-muted);
  flex-shrink: 0;
}

/* ==========================================================================
   5. INTERACTIVE QUANTITATIVE SANDBOX
   ========================================================================== */
.sandbox-wrapper {
  background: var(--bg-surface);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
  overflow: hidden;
}

.sandbox-tabs-bar {
  display: flex;
  background: var(--bg-elevated);
  border-bottom: 1px solid var(--border-hairline);
  overflow-x: auto;
}

.sandbox-tab-btn {
  flex: 1;
  min-width: 230px;
  padding: 0.9rem 1.2rem;
  background: transparent;
  border: none;
  border-bottom: 3px solid transparent;
  border-right: 1px solid var(--border-hairline);
  font-family: var(--font-sans);
  font-size: 0.83rem;
  font-weight: 600;
  color: var(--ink-secondary);
  cursor: pointer;
  text-align: left;
  transition: all 0.15s ease;
}

.sandbox-tab-btn:hover {
  background: var(--bg-subtle);
  color: var(--ink-primary);
}

.sandbox-tab-btn[aria-selected="true"] {
  background: var(--bg-surface);
  color: var(--mod-1-color);
  border-bottom-color: var(--mod-1-color);
}

.sandbox-tab-kicker {
  display: block;
  font-family: var(--font-mono);
  font-size: 0.67rem;
  color: var(--ink-muted);
  margin-bottom: 0.15rem;
}

.sandbox-body {
  display: grid;
  grid-template-columns: 370px 1fr;
}

.sandbox-controls {
  padding: 1.4rem;
  border-right: 1px solid var(--border-hairline);
  background: var(--bg-canvas);
  display: flex;
  flex-direction: column;
  gap: 1.05rem;
}

.control-group {
  display: flex;
  flex-direction: column;
  gap: 0.32rem;
}

.control-label-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.79rem;
  font-weight: 600;
  color: var(--ink-primary);
}

.control-val-badge {
  font-family: var(--font-mono);
  font-size: 0.74rem;
  background: var(--bg-elevated);
  padding: 0.1rem 0.45rem;
  border-radius: var(--radius-xs);
  border: 1px solid var(--border-hairline);
  color: var(--mod-1-color);
  flex-shrink: 0;
}

.control-hint {
  font-size: 0.73rem;
  color: var(--ink-muted);
  line-height: 1.42;
}

input[type="range"] {
  width: 100%;
  accent-color: var(--mod-1-color);
  cursor: pointer;
}

.sandbox-preset-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  padding-top: 0.45rem;
  border-top: 1px dashed var(--border-hairline);
}

.btn-preset {
  font-family: var(--font-mono);
  font-size: 0.69rem;
  padding: 0.26rem 0.55rem;
  background: var(--bg-surface);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-xs);
  color: var(--ink-secondary);
  cursor: pointer;
  transition: all 0.15s ease;
}

.btn-preset:hover {
  border-color: var(--mod-1-color);
  color: var(--mod-1-color);
}

.sandbox-viz-panel {
  padding: 1.4rem;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  gap: 1rem;
}

.canvas-frame {
  position: relative;
  width: 100%;
  height: 315px;
  background: var(--bg-canvas);
  border: 1px solid var(--border-hairline);
  border-radius: var(--radius-sm);
  overflow: hidden;
}

.canvas-frame canvas {
  width: 100%;
  height: 100%;
  display: block;
}

.sandbox-metrics-strip {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0.75rem;
}

.metric-box {
  background: var(--bg-elevated);
  border: 1px solid var(--border-hairline);
  border-radius: var(--radius-sm);
  padding: 0.65rem 0.8rem;
}

.metric-box-label {
  font-family: var(--font-mono);
  font-size: 0.67rem;
  color: var(--ink-muted);
  text-transform: uppercase;
}

.metric-box-value {
  font-family: var(--font-mono);
  font-size: 1rem;
  font-weight: 700;
  color: var(--ink-primary);
  margin-top: 0.15rem;
}

/* ==========================================================================
   6. REDESIGNED CURRICULUM EXPLORER WITH STICKY LEFT INDEX RAIL
   ========================================================================== */
.curriculum-toolbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
  flex-wrap: wrap;
  margin-bottom: 1.5rem;
  background: var(--bg-surface);
  padding: 0.85rem 1.15rem;
  border: 1px solid var(--border-hairline);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-xs);
}

.filter-pills {
  display: flex;
  flex-wrap: wrap;
  gap: 0.42rem;
}

.filter-btn {
  padding: 0.36rem 0.75rem;
  font-size: 0.77rem;
  font-weight: 600;
  border-radius: 999px;
  border: 1px solid var(--border-hairline);
  background: var(--bg-canvas);
  color: var(--ink-secondary);
  cursor: pointer;
  transition: all 0.15s ease;
}

.filter-btn:hover {
  border-color: var(--ink-secondary);
  color: var(--ink-primary);
}

.filter-btn.active {
  background: var(--ink-primary);
  color: var(--bg-canvas);
  border-color: var(--ink-primary);
}

.search-input-wrap {
  position: relative;
  min-width: 260px;
  flex: 0 1 340px;
}

.search-input {
  width: 100%;
  padding: 0.44rem 0.85rem 0.44rem 2.1rem;
  font-family: var(--font-sans);
  font-size: 0.81rem;
  background: var(--bg-canvas);
  color: var(--ink-primary);
  border: 1px solid var(--border-strong);
  border-radius: 999px;
}

.search-input:focus {
  outline: 2px solid var(--border-focus);
  border-color: transparent;
}

.search-icon {
  position: absolute;
  left: 0.75rem;
  top: 50%;
  transform: translateY(-50%);
  font-size: 0.82rem;
  color: var(--ink-muted);
  pointer-events: none;
}

/* Two-Column Curriculum Layout: Sticky Left Index Rail + Lecture Stack */
.curriculum-workspace {
  display: grid;
  grid-template-columns: 255px 1fr;
  gap: 1.5rem;
  align-items: start;
}

.lecture-rail {
  position: sticky;
  top: 4.5rem;
  background: var(--bg-surface);
  border: 1px solid var(--border-hairline);
  border-radius: var(--radius-md);
  padding: 0.85rem;
  box-shadow: var(--shadow-xs);
}

.rail-header {
  font-family: var(--font-mono);
  font-size: 0.69rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--ink-muted);
  padding: 0.2rem 0.4rem 0.55rem;
  border-bottom: 1px solid var(--border-hairline);
  margin-bottom: 0.45rem;
}

.rail-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 0.22rem;
}

.rail-link {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.42rem 0.5rem;
  border-radius: var(--radius-sm);
  text-decoration: none;
  color: var(--ink-secondary);
  font-size: 0.76rem;
  font-weight: 500;
  transition: background-color 0.15s ease, color 0.15s ease;
}

.rail-link:hover {
  background: var(--bg-elevated);
  color: var(--ink-primary);
}

.rail-dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  flex-shrink: 0;
}

.rail-dot-1 { background: var(--mod-1-color); }
.rail-dot-2 { background: var(--mod-2-color); }
.rail-dot-3 { background: var(--mod-3-color); }
.rail-dot-4 { background: var(--mod-4-color); }

.rail-code {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  font-weight: 700;
  color: var(--ink-muted);
  flex-shrink: 0;
}

.rail-title-text {
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.lectures-stack {
  display: flex;
  flex-direction: column;
  gap: 1.65rem;
  min-width: 0;
}

.lecture-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-hairline);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  overflow: hidden;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.lecture-card:hover {
  border-color: var(--border-strong);
  box-shadow: var(--shadow-md);
}

.lecture-card-header {
  padding: 1.35rem 1.55rem;
  border-bottom: 1px solid var(--border-hairline);
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 1.15rem;
  flex-wrap: wrap;
}

.lecture-meta-top {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  flex-wrap: wrap;
  margin-bottom: 0.45rem;
}

.lecture-num-badge {
  font-family: var(--font-mono);
  font-size: 0.73rem;
  font-weight: 700;
  padding: 0.18rem 0.55rem;
  background: var(--ink-primary);
  color: var(--bg-canvas);
  border-radius: var(--radius-xs);
}

.lecture-duration-badge {
  font-family: var(--font-mono);
  font-size: 0.71rem;
  color: var(--ink-muted);
  background: var(--bg-elevated);
  padding: 0.16rem 0.5rem;
  border-radius: var(--radius-xs);
}

.lecture-title {
  font-family: var(--font-serif);
  font-size: 1.34rem;
  font-weight: 700;
  color: var(--ink-primary);
  margin: 0 0 0.42rem;
}

.lecture-thesis {
  font-size: 0.88rem;
  color: var(--ink-secondary);
  margin: 0;
  max-width: 82ch;
}

.lecture-header-actions {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  flex-shrink: 0;
}

.complete-toggle-label {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  font-family: var(--font-mono);
  font-size: 0.74rem;
  padding: 0.34rem 0.68rem;
  background: var(--bg-elevated);
  border: 1px solid var(--border-hairline);
  border-radius: var(--radius-sm);
  cursor: pointer;
  user-select: none;
  color: var(--ink-secondary);
}

.complete-toggle-label input {
  accent-color: var(--mod-2-color);
  cursor: pointer;
}

/* Lecture Sub-Navigation Tabs */
.lecture-subnav {
  display: flex;
  background: var(--bg-elevated);
  border-bottom: 1px solid var(--border-hairline);
  padding: 0 1.2rem;
  gap: 0.25rem;
  overflow-x: auto;
}

.lecture-tab-btn {
  padding: 0.66rem 0.95rem;
  background: transparent;
  border: none;
  border-bottom: 2px solid transparent;
  font-family: var(--font-sans);
  font-size: 0.79rem;
  font-weight: 600;
  color: var(--ink-secondary);
  cursor: pointer;
  white-space: nowrap;
  transition: all 0.15s ease;
}

.lecture-tab-btn:hover {
  color: var(--ink-primary);
}

.lecture-tab-btn[aria-expanded="true"] {
  color: var(--mod-1-color);
  border-bottom-color: var(--mod-1-color);
  background: var(--bg-surface);
}

/* Nested wrapper for hidden="until-found" compliance */
.lecture-panel-inner {
  padding: 1.4rem 1.55rem;
}

.lecture-panel-grid {
  display: grid;
  grid-template-columns: 1.32fr 1fr;
  gap: 1.4rem;
  align-items: start;
}

.timeline-list {
  display: flex;
  flex-direction: column;
  gap: 0.8rem;
}

.timeline-step {
  display: grid;
  grid-template-columns: 108px 1fr;
  gap: 0.85rem;
  padding: 0.82rem 0.95rem;
  background: var(--bg-canvas);
  border: 1px solid var(--border-hairline);
  border-radius: var(--radius-sm);
}

.time-badge {
  font-family: var(--font-mono);
  font-size: 0.71rem;
  font-weight: 700;
  color: var(--mod-1-color);
  background: var(--mod-1-bg);
  border: 1px solid var(--mod-1-border);
  padding: 0.2rem 0.42rem;
  border-radius: var(--radius-xs);
  height: fit-content;
  text-align: center;
}

.timeline-step-title {
  font-weight: 700;
  font-size: 0.86rem;
  color: var(--ink-primary);
  margin: 0 0 0.28rem;
}

.timeline-step-points {
  margin: 0;
  padding-left: 1.1rem;
  font-size: 0.81rem;
  color: var(--ink-secondary);
}

.timeline-step-points li {
  margin-bottom: 0.2rem;
}

.formal-math-box {
  background: var(--bg-elevated);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-md);
  padding: 1.1rem 1.2rem;
}

.formal-math-header {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--ink-secondary);
  margin-bottom: 0.5rem;
  display: flex;
  justify-content: space-between;
}

.formal-math-formula {
  background: var(--bg-surface);
  border: 1px solid var(--border-hairline);
  border-radius: var(--radius-sm);
  padding: 0.8rem;
  margin-bottom: 0.7rem;
  overflow-x: auto;
  font-size: 0.88rem;
}

.formal-math-note {
  font-size: 0.79rem;
  color: var(--ink-secondary);
  margin: 0 0 0.8rem;
}

.concept-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem;
}

.concept-tag {
  font-family: var(--font-mono);
  font-size: 0.69rem;
  padding: 0.16rem 0.48rem;
  background: var(--bg-surface);
  border: 1px solid var(--border-hairline);
  border-radius: var(--radius-xs);
  color: var(--ink-body);
}

/* 12-Slide Grid */
.slides-grid-toolbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 0.95rem;
  flex-wrap: wrap;
  gap: 0.75rem;
}

.slides-mini-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: 0.7rem;
}

.slide-mini-card {
  background: var(--bg-canvas);
  border: 1px solid var(--border-hairline);
  border-radius: var(--radius-sm);
  padding: 0.72rem 0.85rem;
  cursor: pointer;
  transition: border-color 0.15s ease, transform 0.15s ease;
}

.slide-mini-card:hover {
  border-color: var(--mod-1-color);
  transform: translateY(-1px);
}

.slide-mini-top {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 0.32rem;
}

.slide-idx {
  font-family: var(--font-mono);
  font-size: 0.67rem;
  font-weight: 700;
  color: var(--ink-muted);
}

.slide-type-pill {
  font-family: var(--font-mono);
  font-size: 0.65rem;
  padding: 0.1rem 0.38rem;
  background: var(--bg-elevated);
  border-radius: 3px;
  color: var(--mod-1-color);
}

.slide-mini-title {
  font-weight: 700;
  font-size: 0.82rem;
  color: var(--ink-primary);
  margin: 0 0 0.24rem;
}

.slide-mini-desc {
  font-size: 0.75rem;
  color: var(--ink-secondary);
  margin: 0;
}

/* Workshop & Readings */
.workshop-box {
  background: var(--bg-canvas);
  border: 1px solid var(--border-strong);
  border-left: 4px solid var(--mod-2-color);
  border-radius: var(--radius-md);
  padding: 1.2rem 1.35rem;
}

.workshop-title-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 0.7rem;
}

.workshop-title {
  font-family: var(--font-serif);
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--ink-primary);
  margin: 0;
}

.workshop-steps-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
  gap: 0.8rem;
  margin-top: 0.85rem;
}

.workshop-role-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-hairline);
  border-radius: var(--radius-sm);
  padding: 0.78rem 0.9rem;
}

.workshop-role-card h5 {
  margin: 0 0 0.32rem;
  font-size: 0.81rem;
  color: var(--ink-primary);
}

.workshop-role-card p {
  margin: 0;
  font-size: 0.77rem;
  color: var(--ink-secondary);
}

.readings-layout {
  display: grid;
  grid-template-columns: 1.2fr 1fr;
  gap: 1.35rem;
}

.paper-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
}

.paper-item {
  background: var(--bg-canvas);
  border: 1px solid var(--border-hairline);
  border-radius: var(--radius-sm);
  padding: 0.72rem 0.9rem;
}

.paper-cite {
  font-family: var(--font-serif);
  font-size: 0.85rem;
  color: var(--ink-primary);
  font-weight: 600;
}

.paper-venue {
  font-family: var(--font-mono);
  font-size: 0.69rem;
  color: var(--mod-1-color);
  margin-top: 0.18rem;
}

.socratic-box {
  background: var(--bg-elevated);
  border: 1px solid var(--border-hairline);
  border-radius: var(--radius-sm);
  padding: 0.95rem 1.1rem;
}

.socratic-q {
  font-family: var(--font-serif);
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--ink-primary);
  margin: 0 0 0.7rem;
}

.socratic-details {
  font-size: 0.79rem;
  color: var(--ink-secondary);
  border-top: 1px dashed var(--border-strong);
  padding-top: 0.55rem;
}

.socratic-details summary {
  font-weight: 600;
  cursor: pointer;
  color: var(--mod-1-color);
}

/* ==========================================================================
   7. NATIVE LIGHT-DISMISS SLIDE MODAL DIALOG
   ========================================================================== */
dialog.slide-modal {
  width: min(960px, 94vw);
  max-height: 88vh;
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-lg);
  background: var(--bg-surface);
  color: var(--ink-body);
  padding: 0;
  box-shadow: var(--shadow-lg);
  overflow: hidden;
}

dialog.slide-modal::backdrop {
  background-color: rgba(9, 12, 18, 0.7);
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
}

.modal-inner {
  display: flex;
  flex-direction: column;
  height: 100%;
}

.modal-topbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0.85rem 1.3rem;
  background: var(--bg-elevated);
  border-bottom: 1px solid var(--border-hairline);
}

.modal-slide-stage {
  padding: 2.1rem 2.4rem;
  min-height: 350px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  background:
    radial-gradient(circle at 92% 12%, var(--mod-1-bg), transparent 40%),
    var(--bg-canvas);
}

.stage-slide-counter {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--mod-1-color);
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.stage-slide-title {
  font-family: var(--font-serif);
  font-size: 1.7rem;
  color: var(--ink-primary);
  margin: 0.45rem 0 0.95rem;
}

.stage-slide-body {
  font-size: 0.98rem;
  line-height: 1.72;
  color: var(--ink-body);
  background: var(--bg-surface);
  border: 1px solid var(--border-hairline);
  border-left: 4px solid var(--mod-1-color);
  padding: 1.1rem 1.3rem;
  border-radius: var(--radius-sm);
}

.stage-speaker-notes {
  margin-top: 1.2rem;
  padding: 0.8rem 1.05rem;
  background: var(--bg-elevated);
  border-radius: var(--radius-sm);
  font-size: 0.82rem;
  color: var(--ink-secondary);
}

.modal-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0.8rem 1.3rem;
  background: var(--bg-surface);
  border-top: 1px solid var(--border-hairline);
}

/* ==========================================================================
   8. FOOTER & RESPONSIVE BREAKPOINTS
   ========================================================================== */
.site-footer {
  border-top: 1px solid var(--border-hairline);
  background: var(--bg-surface);
  padding: 2.4rem 1.5rem;
  font-size: 0.8rem;
  color: var(--ink-muted);
}

.site-footer-inner {
  max-width: 1440px;
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 1rem;
}

@media (max-width: 1120px) {
  .hero-container,
  .sandbox-body,
  .curriculum-workspace,
  .lecture-panel-grid,
  .readings-layout {
    grid-template-columns: 1fr;
  }
  .lecture-rail {
    position: static;
  }
  .rail-list {
    flex-direction: row;
    flex-wrap: wrap;
  }
  .module-pillars-grid,
  .meta-strip-inner {
    grid-template-columns: repeat(2, 1fr);
  }
  .sandbox-controls {
    border-right: none;
    border-bottom: 1px solid var(--border-hairline);
  }
}

@media (max-width: 640px) {
  .module-pillars-grid,
  .meta-strip-inner,
  .hero-metrics-ribbon,
  .sandbox-metrics-strip {
    grid-template-columns: 1fr;
  }
  .ribbon-cell {
    border-right: none;
    border-bottom: 1px solid var(--border-hairline);
  }
  .timeline-step {
    grid-template-columns: 1fr;
  }
}