/* ========================================
   Modern Computer Vision — Course Website
   Dark + Techy + Minimal
   ======================================== */

:root {
  --bg-primary: #0d1117;
  --bg-secondary: #161b22;
  --bg-card: #1c2128;
  --bg-hover: #21262d;
  --border: #30363d;
  --border-light: #21262d;
  --text-primary: #e6edf3;
  --text-secondary: #8b949e;
  --text-muted: #6e7681;
  --accent: #58a6ff;
  --accent-dim: #1f6feb;
  --accent-glow: rgba(88, 166, 255, 0.15);
  --teal: #3fb8af;
  --teal-dim: rgba(63, 184, 175, 0.15);
  --purple: #bc8cff;
  --orange: #f0883e;
  --green: #56d364;
  --red: #f85149;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
  --max-width: 1100px;
  --nav-height: 60px;
}

* { margin: 0; padding: 0; box-sizing: border-box; }

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

body {
  font-family: var(--font-sans);
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

/* ---- NAV ---- */
nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(13, 17, 23, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  height: var(--nav-height);
}

.nav-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
}

.nav-brand {
  display: flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
  color: var(--text-primary);
}

.nav-brand img {
  height: 32px;
  width: auto;
  filter: brightness(0) invert(1);
  opacity: 0.9;
}

.nav-brand span {
  font-weight: 600;
  font-size: 1.05rem;
  letter-spacing: -0.01em;
}

.nav-links {
  display: flex;
  gap: 8px;
  list-style: none;
}

.nav-links a {
  display: block;
  padding: 8px 16px;
  border-radius: 8px;
  text-decoration: none;
  color: var(--text-secondary);
  font-size: 0.9rem;
  font-weight: 500;
  transition: all 0.2s;
}

.nav-links a:hover {
  color: var(--text-primary);
  background: var(--bg-hover);
}

.nav-links a.active {
  color: var(--accent);
  background: var(--bg-hover);
}

/* Anchor links (in-page shortcuts) get a subtle dot indicator */
.nav-links a.nav-anchor {
  color: var(--text-muted);
  font-size: 0.82rem;
  position: relative;
  padding-left: 22px;
}

.nav-links a.nav-anchor::before {
  content: '#';
  position: absolute;
  left: 10px;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  opacity: 0.5;
}

.nav-links a.nav-anchor:hover {
  color: var(--text-secondary);
}

/* Hamburger */
.nav-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
}

.nav-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--text-secondary);
  margin: 5px 0;
  border-radius: 2px;
  transition: all 0.3s;
}

@media (max-width: 640px) {
  .nav-toggle { display: block; }

  .nav-links {
    display: none;
    position: absolute;
    top: var(--nav-height);
    left: 0;
    right: 0;
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border);
    flex-direction: column;
    padding: 12px 16px;
    gap: 4px;
  }

  .nav-links.open { display: flex; }

  .nav-links a {
    padding: 12px 16px;
    border-radius: 8px;
  }
}

/* ---- HERO ---- */
.hero {
  position: relative;
  padding: 80px 24px 60px;
  text-align: center;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: -120px;
  left: 50%;
  transform: translateX(-50%);
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, var(--accent-glow) 0%, transparent 70%);
  pointer-events: none;
}

.hero-content {
  position: relative;
  max-width: 720px;
  margin: 0 auto;
}

.hero-badge {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--teal);
  background: var(--teal-dim);
  padding: 4px 14px;
  border-radius: 100px;
  margin-bottom: 20px;
}

.hero h1 {
  font-size: 2.8rem;
  font-weight: 700;
  letter-spacing: -0.03em;
  line-height: 1.15;
  margin-bottom: 16px;
}

.hero h1 .accent {
  background: linear-gradient(135deg, var(--accent), var(--teal));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero .subtitle {
  font-size: 1.15rem;
  color: var(--text-secondary);
  margin-bottom: 32px;
  max-width: 540px;
  margin-left: auto;
  margin-right: auto;
}

.hero-buttons {
  display: flex;
  gap: 12px;
  justify-content: center;
  flex-wrap: wrap;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 22px;
  border-radius: 10px;
  font-size: 0.9rem;
  font-weight: 500;
  text-decoration: none;
  transition: all 0.2s;
  cursor: pointer;
  border: none;
}

.btn-primary {
  background: var(--accent-dim);
  color: #fff;
}

.btn-primary:hover {
  background: var(--accent);
  color: #fff;
}

.btn-secondary {
  background: var(--bg-card);
  color: var(--text-secondary);
  border: 1px solid var(--border);
}

.btn-secondary:hover {
  color: var(--text-primary);
  border-color: var(--text-muted);
}

/* ---- HERO IMAGE ---- */
.hero-image {
  margin: 48px auto 0;
  max-width: 800px;
  overflow: hidden;
  border: none;
  border-radius: 0;
  box-shadow: none;
  /* Fade edges into background */
  -webkit-mask-image: linear-gradient(to right, transparent 0%, black 10%, black 90%, transparent 100%);
  mask-image: linear-gradient(to right, transparent 0%, black 10%, black 90%, transparent 100%);
}

.hero-image img {
  display: block;
  width: 100%;
  height: auto;
}

/* ---- SECTION ---- */
.section {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 60px 24px;
}

.section-title {
  font-size: 1.5rem;
  font-weight: 600;
  margin-bottom: 8px;
  letter-spacing: -0.02em;
}

.section-subtitle {
  color: var(--text-secondary);
  margin-bottom: 32px;
  font-size: 0.95rem;
}

/* ---- INFO CARDS ---- */
.cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 16px;
}

.card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 24px;
  transition: border-color 0.2s;
}

.card:hover {
  border-color: var(--text-muted);
}

.card-icon {
  font-size: 1.5rem;
  margin-bottom: 12px;
}

.card h3 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 8px;
}

.card p {
  color: var(--text-secondary);
  font-size: 0.88rem;
  line-height: 1.55;
}

/* Compact card variants */
.cards-compact {
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
}

.card-sm {
  padding: 16px 20px;
}

.card-sm h3 {
  font-size: 0.9rem;
  margin-bottom: 6px;
}

.card-sm p {
  font-size: 0.82rem;
}

.card-sm .card-icon {
  display: none;
}

/* ---- OVERVIEW ---- */
.overview-text {
  color: var(--text-secondary);
  font-size: 0.95rem;
  line-height: 1.7;
  max-width: 640px;
  margin: 0 auto;
  text-align: center;
}

.overview-text p + p {
  margin-top: 12px;
}

/* ---- STAFF ---- */
.staff-grid {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
}

.staff-card {
  display: flex;
  align-items: center;
  gap: 16px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 16px 20px;
  min-width: 260px;
  flex: 1;
}

.staff-avatar {
  width: 56px;
  height: 56px;
  border-radius: 50%;
  background: var(--bg-hover);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.3rem;
  flex-shrink: 0;
  overflow: hidden;
}

.staff-avatar img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  border-radius: 50%;
}

.staff-info h4 {
  font-size: 0.92rem;
  font-weight: 600;
}

.staff-info p {
  font-size: 0.82rem;
  color: var(--text-secondary);
}

.staff-info a {
  color: var(--accent);
  text-decoration: none;
  font-size: 0.82rem;
}

.staff-info a:hover { text-decoration: underline; }

/* ---- SCHEDULE TABLE ---- */
.schedule-wrap {
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  border: 1px solid var(--border);
  border-radius: 12px;
}

.schedule-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.88rem;
  min-width: 860px;
}

.schedule-table thead {
  background: var(--bg-secondary);
}

.schedule-table th {
  padding: 14px 16px;
  text-align: left;
  font-weight: 600;
  font-size: 0.78rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--text-secondary);
  border-bottom: 1px solid var(--border);
  white-space: nowrap;
}

.schedule-table td {
  padding: 14px 16px;
  vertical-align: top;
  border-bottom: 1px solid var(--border-light);
}

.schedule-table tbody tr:hover {
  background: var(--bg-hover);
}

.schedule-table .wk-num {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--text-muted);
  text-align: center;
  width: 50px;
}

.schedule-table .date-cell {
  color: var(--text-secondary);
  font-size: 0.84rem;
  white-space: nowrap;
}

.schedule-table .lecture-cell {
  font-weight: 500;
  color: var(--text-primary);
}

.schedule-table .tutorial-cell {
  color: var(--text-secondary);
  font-style: italic;
}

/* Assignment links */
.hw-links {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
}

.hw-link {
  display: inline-flex;
  align-items: center;
  gap: 3px;
  padding: 3px 8px;
  border-radius: 6px;
  font-size: 0.74rem;
  font-weight: 500;
  text-decoration: none;
  transition: all 0.15s;
  white-space: nowrap;
}

.hw-link.theory {
  background: rgba(88, 166, 255, 0.12);
  color: var(--accent);
  border: 1px solid rgba(88, 166, 255, 0.2);
}

.hw-link.theory:hover {
  background: rgba(88, 166, 255, 0.22);
}

.hw-link.scratch {
  background: rgba(188, 140, 255, 0.12);
  color: var(--purple);
  border: 1px solid rgba(188, 140, 255, 0.2);
}

.hw-link.scratch:hover {
  background: rgba(188, 140, 255, 0.22);
}

.hw-link.applied {
  background: rgba(63, 184, 175, 0.12);
  color: var(--teal);
  border: 1px solid rgba(63, 184, 175, 0.2);
}

.hw-link.applied:hover {
  background: rgba(63, 184, 175, 0.22);
}

.hw-link svg {
  width: 11px;
  height: 11px;
  flex-shrink: 0;
}

/* Link rows with labels */
.hw-links-group {
  margin-top: 4px;
}

.hw-links-label {
  font-size: 0.68rem;
  font-weight: 500;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: 4px;
  display: block;
}

.hw-links-row {
  display: flex;
  gap: 5px;
  flex-wrap: nowrap;
}

.hw-links-group + .hw-links-group {
  margin-top: 6px;
}

/* Upload links — same colors as download but dashed border */
.hw-link.theory-up {
  background: rgba(88, 166, 255, 0.06);
  color: var(--accent);
  border: 1px dashed rgba(88, 166, 255, 0.3);
}

.hw-link.theory-up:hover {
  background: rgba(88, 166, 255, 0.15);
}

.hw-link.scratch-up {
  background: rgba(188, 140, 255, 0.06);
  color: var(--purple);
  border: 1px dashed rgba(188, 140, 255, 0.3);
}

.hw-link.scratch-up:hover {
  background: rgba(188, 140, 255, 0.15);
}

.hw-link.applied-up {
  background: rgba(63, 184, 175, 0.06);
  color: var(--teal);
  border: 1px dashed rgba(63, 184, 175, 0.3);
}

.hw-link.applied-up:hover {
  background: rgba(63, 184, 175, 0.15);
}

.hw-link .ul-icon {
  width: 12px;
  height: 12px;
  vertical-align: -1px;
}

/* HW badge */
.hw-badge {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  font-weight: 600;
  padding: 2px 8px;
  border-radius: 6px;
  margin-bottom: 4px;
  letter-spacing: 0.03em;
}

.hw-badge.b1 { background: #042C53; color: #B5D4F4; }
.hw-badge.b2 { background: #26215C; color: #CECBF6; }
.hw-badge.b3 { background: #412402; color: #FAC775; }
.hw-badge.b4 { background: #4A1B0C; color: #F5C4B3; }
.hw-badge.b5 { background: #04342C; color: #9FE1CB; }

.hw-title {
  font-weight: 500;
  font-size: 0.86rem;
  margin-bottom: 2px;
}

.hw-desc {
  font-size: 0.78rem;
  color: var(--text-muted);
  line-height: 1.4;
}

/* Resources */
.resource-link {
  color: var(--accent);
  text-decoration: none;
  font-size: 0.8rem;
  display: inline-block;
  padding: 2px 0;
  white-space: nowrap;
}
.resource-link + br + .resource-link {
  border-top: 1px solid #e8e8e8;
  margin-top: 2px;
  padding-top: 4px;
}

.resource-link:hover { text-decoration: underline; }

/* HW cell — boxed assignment cell (rowspan merges it visually) */
.hw-cell {
  background: var(--bg-secondary);
  border: 1px solid var(--border) !important;
  border-radius: 8px;
  padding: 14px 16px;
  vertical-align: top;
}

/* HW due date */
.hw-due {
  display: block;
  font-size: 0.72rem;
  color: var(--text-muted);
  margin-top: 8px;
  font-family: var(--font-mono);
}

/* Group separator */
.schedule-table .group-sep td {
  padding: 0;
  height: 8px;
  background: var(--bg-primary);
  border: none;
}

/* Final row */
.final-row td {
  color: var(--text-muted);
  font-style: italic;
  text-align: center;
}

/* ---- FOOTER ---- */
footer {
  border-top: 1px solid var(--border);
  padding: 32px 24px;
  text-align: center;
  color: var(--text-muted);
  font-size: 0.82rem;
}

footer a {
  color: var(--text-secondary);
  text-decoration: none;
}

footer a:hover { color: var(--text-primary); }

/* ---- FORMS ---- */
.form-group {
  margin-bottom: 20px;
}

.form-label {
  display: block;
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--text-secondary);
  margin-bottom: 6px;
}

.form-input {
  width: 100%;
  padding: 10px 14px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: var(--bg-card);
  color: var(--text-primary);
  font-family: var(--font-sans);
  font-size: 0.9rem;
  transition: border-color 0.2s;
  outline: none;
}

.form-input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-glow);
}

.form-input::placeholder {
  color: var(--text-muted);
}

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
}

@media (max-width: 640px) {
  .form-row { grid-template-columns: 1fr; }
}

.form-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 32px;
  max-width: 600px;
}

.form-note {
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-top: 16px;
}

/* Member row with remove */
.member-row {
  display: grid;
  grid-template-columns: 1fr 1fr auto;
  gap: 12px;
  align-items: end;
  margin-bottom: 12px;
}

@media (max-width: 640px) {
  .member-row { grid-template-columns: 1fr; }
}

.btn-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: var(--bg-card);
  color: var(--text-muted);
  cursor: pointer;
  transition: all 0.15s;
  font-size: 1.1rem;
}

.btn-icon:hover {
  color: var(--red);
  border-color: var(--red);
}

.btn-add {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 14px;
  border-radius: 8px;
  border: 1px dashed var(--border);
  background: transparent;
  color: var(--text-secondary);
  cursor: pointer;
  font-size: 0.84rem;
  font-family: var(--font-sans);
  transition: all 0.15s;
  margin-bottom: 20px;
}

.btn-add:hover {
  border-color: var(--accent);
  color: var(--accent);
}

/* ---- UTILS ---- */
.divider {
  border: none;
  border-top: 1px solid var(--border);
  margin: 0;
}

@media (max-width: 640px) {
  .hero { padding: 48px 20px 40px; }
  .hero h1 { font-size: 2rem; }
  .hero .subtitle { font-size: 1rem; }
  .section { padding: 40px 20px; }
  .cards { grid-template-columns: 1fr; }
}