/* assets/css/main.css */

/* ═══════════════════════════════════════
   DESIGN TOKENS
═══════════════════════════════════════ */
:root {
  /* Colors */
  --c-bg:          #0F0E17;
  --c-bg-card:     #1A1829;
  --c-bg-card-alt: #211F35;
  --c-accent-gold: #E8A045;
  --c-accent-violet: #7B6FF0;
  --c-accent-teal: #4ECDC4;
  --c-text:        #F0EDE8;
  --c-text-muted:  #9B97A8;
  --c-border:      rgba(255,255,255,0.08);

  /* Gradients */
  --grad-hero: linear-gradient(135deg, #0F0E17 0%, #1A1040 60%, #0F1A2E 100%);
  --grad-card: linear-gradient(135deg, #1A1829, #211F35);

  /* Typography */
  --font-serif: 'Cormorant Garamond', 'Noto Serif TC', Georgia, serif;
  --font-sans:  'IBM Plex Sans', 'Noto Sans TC', system-ui, sans-serif;
  --font-mono:  'JetBrains Mono', 'Fira Code', monospace;

  /* Spacing */
  --space-xs: 0.5rem;
  --space-sm: 1rem;
  --space-md: 2rem;
  --space-lg: 4rem;
  --space-xl: 8rem;

  /* Radius */
  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 20px;

  /* Transitions */
  --transition: 0.25s cubic-bezier(0.4, 0, 0.2, 1);
}

/* ═══════════════════════════════════════
   RESET & BASE
═══════════════════════════════════════ */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

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

body {
  background-color: var(--c-bg);
  color: var(--c-text);
  font-family: var(--font-sans);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3, h4 {
  font-family: var(--font-serif);
  font-weight: 600;
  line-height: 1.2;
  letter-spacing: -0.01em;
}

a { color: var(--c-accent-gold); text-decoration: none; transition: opacity var(--transition); }
a:hover { opacity: 0.8; }

img { max-width: 100%; display: block; }

/* ═══════════════════════════════════════
   LAYOUT UTILITIES
═══════════════════════════════════════ */
.container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 var(--space-md);
}

.section {
  padding: var(--space-lg) 0;
}

.section-title {
  font-family: var(--font-serif);
  font-size: clamp(1.8rem, 4vw, 2.5rem);
  color: var(--c-text);
  margin-bottom: var(--space-md);
}

.section-title span {
  color: var(--c-accent-gold);
}

/* ═══════════════════════════════════════
   SCROLL ANIMATIONS
═══════════════════════════════════════ */
.fade-up {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}
.fade-up.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ═══════════════════════════════════════
   NAVIGATION
═══════════════════════════════════════ */
.site-nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(15, 14, 23, 0.85);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--c-border);
  padding: var(--space-sm) 0;
}

.site-nav .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-sm);
}

.nav-logo {
  font-family: var(--font-serif);
  font-size: 1.1rem;
  color: var(--c-text);
  font-weight: 600;
  flex-shrink: 0;
}

.nav-logo span { color: var(--c-accent-gold); }

.nav-links {
  display: flex;
  gap: var(--space-md);
  list-style: none;
  flex-wrap: wrap;
}

.nav-links a {
  color: var(--c-text-muted);
  font-size: 0.9rem;
  font-family: var(--font-sans);
  transition: color var(--transition);
  letter-spacing: 0.02em;
}

.nav-links a:hover,
.nav-links a.active { color: var(--c-accent-gold); opacity: 1; }

/* Mobile nav toggle */
.nav-toggle {
  display: none;
  background: none;
  border: 1px solid var(--c-border);
  color: var(--c-text);
  padding: 6px 10px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  font-size: 1rem;
}

@media (max-width: 700px) {
  .nav-toggle { display: block; }
  .nav-links {
    display: none;
    position: absolute;
    top: 100%;
    left: 0; right: 0;
    background: var(--c-bg);
    border-top: 1px solid var(--c-border);
    flex-direction: column;
    padding: var(--space-sm) var(--space-md);
    gap: var(--space-sm);
  }
  .nav-links.open { display: flex; }
}

/* ═══════════════════════════════════════
   HERO
═══════════════════════════════════════ */
.hero {
  position: relative;
  min-height: 88vh;
  display: flex;
  align-items: center;
  background: var(--grad-hero);
  overflow: hidden;
}

/* Noise texture overlay */
.hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 256 256' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='noise'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23noise)' opacity='0.04'/%3E%3C/svg%3E");
  opacity: 0.4;
  pointer-events: none;
}

/* Glowing orb effects */
.hero::after {
  content: '';
  position: absolute;
  width: 600px; height: 600px;
  background: radial-gradient(circle, rgba(123,111,240,0.15) 0%, transparent 70%);
  top: -100px; right: -100px;
  pointer-events: none;
}

.hero-content {
  position: relative;
  z-index: 1;
}

.hero-eyebrow {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--c-accent-gold);
  letter-spacing: 0.15em;
  text-transform: uppercase;
  margin-bottom: var(--space-sm);
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.hero-eyebrow::before {
  content: '✦';
}

.hero-title {
  font-family: var(--font-serif);
  font-size: clamp(2.5rem, 7vw, 5rem);
  font-weight: 700;
  line-height: 1.05;
  color: var(--c-text);
  margin-bottom: var(--space-sm);
}

.hero-title-en {
  font-family: var(--font-sans);
  font-size: clamp(1rem, 2.5vw, 1.4rem);
  color: var(--c-text-muted);
  font-weight: 300;
  letter-spacing: 0.02em;
  margin-bottom: var(--space-md);
}

.hero-meta {
  font-size: 0.85rem;
  color: var(--c-text-muted);
  margin-top: var(--space-md);
  font-family: var(--font-mono);
  letter-spacing: 0.05em;
}

.hero-meta span { color: var(--c-accent-violet); }

.hero-actions {
  display: flex;
  gap: var(--space-sm);
  flex-wrap: wrap;
  margin-bottom: var(--space-sm);
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.75rem 1.5rem;
  border-radius: var(--radius-sm);
  font-family: var(--font-sans);
  font-size: 0.9rem;
  font-weight: 500;
  transition: all var(--transition);
  cursor: pointer;
  border: none;
  text-decoration: none;
}

.btn-primary {
  background: var(--c-accent-gold);
  color: #0F0E17;
}
.btn-primary:hover { background: #f5b05a; opacity: 1; transform: translateY(-2px); }

.btn-outline {
  background: transparent;
  color: var(--c-text);
  border: 1px solid var(--c-border);
}
.btn-outline:hover { border-color: var(--c-accent-gold); color: var(--c-accent-gold); opacity: 1; }

/* ═══════════════════════════════════════
   STATS BAR
═══════════════════════════════════════ */
.stats-bar {
  background: var(--c-bg-card);
  border-top: 1px solid var(--c-border);
  border-bottom: 1px solid var(--c-border);
  padding: var(--space-sm) 0;
}

.stats-bar .container {
  display: flex;
  justify-content: center;
  gap: var(--space-lg);
  flex-wrap: wrap;
}

.stat-item {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.85rem;
  color: var(--c-text-muted);
  font-family: var(--font-mono);
}

.stat-item strong {
  color: var(--c-accent-gold);
  font-size: 1.2rem;
  font-family: var(--font-serif);
}

/* ═══════════════════════════════════════
   OVERVIEW SECTION
═══════════════════════════════════════ */
.overview-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-lg);
  align-items: center;
}

@media (max-width: 768px) { .overview-grid { grid-template-columns: 1fr; } }

.overview-text p {
  color: var(--c-text-muted);
  line-height: 1.85;
  margin-bottom: var(--space-sm);
}

/* Grading Donut Chart */
.grading-chart {
  background: var(--grad-card);
  border: 1px solid var(--c-border);
  border-radius: var(--radius-lg);
  padding: var(--space-md);
  text-align: center;
}

.grading-chart h3 {
  font-size: 1rem;
  color: var(--c-text-muted);
  font-family: var(--font-sans);
  font-weight: 400;
  margin-bottom: var(--space-md);
  letter-spacing: 0.05em;
}

.donut-container {
  position: relative;
  width: 180px;
  height: 180px;
  margin: 0 auto var(--space-md);
}

.donut-container svg { transform: rotate(-90deg); }

.donut-label {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
}

.donut-label span:first-child {
  font-family: var(--font-serif);
  font-size: 1.8rem;
  color: var(--c-text);
}

.donut-label span:last-child {
  font-size: 0.7rem;
  color: var(--c-text-muted);
  letter-spacing: 0.1em;
}

.grading-legend {
  list-style: none;
  text-align: left;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.grading-legend li {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-size: 0.9rem;
  color: var(--c-text-muted);
}

.legend-dot {
  width: 10px; height: 10px;
  border-radius: 50%;
  flex-shrink: 0;
}

/* ═══════════════════════════════════════
   HIGHLIGHT CARDS
═══════════════════════════════════════ */
.highlights-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--space-sm);
}

.highlight-card {
  background: var(--grad-card);
  border: 1px solid var(--c-border);
  border-radius: var(--radius-md);
  padding: var(--space-md);
  transition: transform var(--transition), border-color var(--transition), box-shadow var(--transition);
  cursor: default;
}

.highlight-card:hover {
  transform: translateY(-4px);
  border-color: var(--c-accent-gold);
  box-shadow: 0 0 24px rgba(232,160,69,0.12);
}

.card-icon {
  font-size: 2rem;
  margin-bottom: var(--space-sm);
}

.card-title {
  font-family: var(--font-serif);
  font-size: 1.2rem;
  color: var(--c-text);
  margin-bottom: var(--space-xs);
}

.card-desc {
  font-size: 0.88rem;
  color: var(--c-text-muted);
  line-height: 1.7;
}

/* ═══════════════════════════════════════
   TEAM SECTION
═══════════════════════════════════════ */
.instructor-card {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  background: var(--grad-card);
  border: 1px solid var(--c-border);
  border-radius: var(--radius-lg);
  padding: var(--space-md);
  margin-bottom: var(--space-md);
  max-width: 500px;
}

.instructor-avatar {
  width: 80px; height: 80px;
  border-radius: 50%;
  object-fit: cover;
  border: 2px solid var(--c-accent-gold);
  flex-shrink: 0;
  background: var(--c-bg-card-alt);
}

.instructor-info h3 {
  font-size: 1.2rem;
  color: var(--c-text);
  margin-bottom: 0.25rem;
}

.instructor-info p {
  font-size: 0.85rem;
  color: var(--c-text-muted);
}

.ta-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
  gap: var(--space-sm);
  margin-top: var(--space-sm);
}

.ta-card {
  background: var(--c-bg-card);
  border: 1px solid var(--c-border);
  border-radius: var(--radius-md);
  padding: var(--space-sm);
  text-align: center;
  transition: border-color var(--transition);
}

.ta-card:hover { border-color: var(--c-accent-violet); }

.ta-avatar {
  width: 56px; height: 56px;
  border-radius: 50%;
  object-fit: cover;
  margin: 0 auto var(--space-xs);
  background: var(--c-bg-card-alt);
}

.ta-name {
  font-size: 0.85rem;
  color: var(--c-text);
  font-weight: 500;
}

.ta-role {
  font-size: 0.75rem;
  color: var(--c-text-muted);
}

/* ═══════════════════════════════════════
   FOOTER
═══════════════════════════════════════ */
.site-footer {
  background: var(--c-bg-card);
  border-top: 1px solid var(--c-border);
  padding: var(--space-md) 0;
  text-align: center;
  font-size: 0.82rem;
  color: var(--c-text-muted);
  line-height: 2;
}

.site-footer a { color: var(--c-text-muted); }
.site-footer a:hover { color: var(--c-accent-gold); opacity: 1; }

/* ═══════════════════════════════════════
   SCHEDULE PAGE
═══════════════════════════════════════ */
.timeline {
  position: relative;
  padding-left: 3rem;
}

.timeline::before {
  content: '';
  position: absolute;
  left: 1rem;
  top: 0; bottom: 0;
  width: 1px;
  background: linear-gradient(to bottom, var(--c-accent-violet), var(--c-accent-gold), transparent);
}

.week-entry {
  position: relative;
  margin-bottom: var(--space-md);
}

.week-entry::before {
  content: '';
  position: absolute;
  left: -2.25rem;
  top: 0.5rem;
  width: 10px; height: 10px;
  border-radius: 50%;
  background: var(--c-accent-gold);
  border: 2px solid var(--c-bg);
  box-shadow: 0 0 8px rgba(232,160,69,0.4);
}

.week-entry.holiday::before { background: var(--c-text-muted); box-shadow: none; }

.week-card {
  background: var(--grad-card);
  border: 1px solid var(--c-border);
  border-radius: var(--radius-md);
  padding: var(--space-sm) var(--space-md);
  transition: border-color var(--transition);
  cursor: pointer;
}

.week-card:hover { border-color: var(--c-accent-gold); }

.week-entry.holiday .week-card {
  opacity: 0.45;
  cursor: default;
  background: none;
}
.week-entry.holiday .week-card:hover { border-color: var(--c-border); }

.week-header {
  display: flex;
  align-items: baseline;
  gap: var(--space-sm);
  flex-wrap: wrap;
}

.week-number {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--c-accent-gold);
  letter-spacing: 0.1em;
  background: rgba(232,160,69,0.1);
  padding: 2px 8px;
  border-radius: 999px;
}

.week-date {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--c-text-muted);
}

.week-title {
  font-family: var(--font-serif);
  font-size: 1.15rem;
  color: var(--c-text);
  margin-top: 0.3rem;
}

.week-subtitle {
  font-size: 0.82rem;
  color: var(--c-accent-violet);
  font-family: var(--font-mono);
  margin-top: 0.15rem;
}

.week-objectives {
  display: none;
  margin-top: var(--space-sm);
  padding-top: var(--space-sm);
  border-top: 1px solid var(--c-border);
}

.week-objectives.open { display: block; }

.week-objectives ul {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.week-objectives li {
  font-size: 0.87rem;
  color: var(--c-text-muted);
  display: flex;
  gap: 0.5rem;
}

.week-objectives li::before { content: '→'; color: var(--c-accent-gold); flex-shrink: 0; }

/* Cluster colors */
.cluster-prompting .week-number { background: rgba(232,160,69,0.15); color: var(--c-accent-gold); }
.cluster-llm       .week-number { background: rgba(123,111,240,0.15); color: var(--c-accent-violet); }
.cluster-agent     .week-number { background: rgba(78,205,196,0.15); color: var(--c-accent-teal); }
.cluster-humanities .week-number { background: rgba(232,160,69,0.12); color: #D4A0FF; }
.cluster-ethics    .week-number { background: rgba(78,205,196,0.12); color: var(--c-accent-teal); }
.cluster-final     .week-number { background: rgba(232,160,69,0.2); color: var(--c-accent-gold); }

/* ═══════════════════════════════════════
   PAGE HERO (inner pages)
═══════════════════════════════════════ */
.page-hero {
  padding: var(--space-lg) 0 var(--space-md);
  border-bottom: 1px solid var(--c-border);
}

.page-hero h1 {
  font-size: clamp(1.8rem, 4vw, 3rem);
  margin-bottom: 0.5rem;
}

.page-hero p {
  color: var(--c-text-muted);
  font-size: 1rem;
}