:root {
  --bg: #0b1726;
  --bg-pattern1: rgba(0, 194, 255, 0.08);
  --bg-pattern2: rgba(255, 255, 255, 0.06);
  --card: #111d30;
  --panel: linear-gradient(135deg, rgba(0, 194, 255, 0.14), rgba(0, 194, 255, 0));
  --accent: #00c2ff;
  --text: #e6eefb;
  --muted: #9bb0cc;
  --border: #1f2c40;
  --header-bg: rgba(11, 23, 38, 0.9);
  --shadow: 0 8px 30px rgba(0, 0, 0, 0.35);
  --radius: 14px;
  --max-width: 1100px;
  font-family: "Inter", system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

:root[data-theme="light"] {
  --bg: #f6f8fb;
  --bg-pattern1: rgba(11, 116, 222, 0.06);
  --bg-pattern2: rgba(15, 27, 45, 0.04);
  --card: #ffffff;
  --panel: linear-gradient(135deg, rgba(11, 116, 222, 0.12), rgba(11, 116, 222, 0.02));
  --accent: #0b74de;
  --text: #0f1b2d;
  --muted: #52607a;
  --border: #d9e2ef;
  --header-bg: rgba(255, 255, 255, 0.92);
  --shadow: 0 8px 30px rgba(15, 27, 45, 0.08);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: radial-gradient(circle at 20% 20%, var(--bg-pattern1), transparent 25%),
    radial-gradient(circle at 80% 0%, var(--bg-pattern2), transparent 30%),
    var(--bg);
  color: var(--text);
  line-height: 1.6;
}

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

a:hover {
  text-decoration: underline;
}

h1, h2, h3 {
  margin: 0 0 0.5rem;
  line-height: 1.2;
}

main {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 110px 20px 60px;
}

.topbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  backdrop-filter: blur(12px);
  background: var(--header-bg);
  border-bottom: 1px solid var(--border);
  z-index: 10;
}

.logo-row {
  display: flex;
  align-items: center;
  gap: 18px;
  padding: 10px 20px 6px;
  max-width: var(--max-width);
  margin: 0 auto;
}

.logo-row img {
  height: 44px;
  object-fit: contain;
  filter: drop-shadow(0 2px 4px rgba(0, 0, 0, 0.3));
}

.nav {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 20px 10px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
}

.nav ul {
  display: flex;
  list-style: none;
  padding: 0;
  margin: 0;
  gap: 14px;
  flex-wrap: wrap;
}

.nav a {
  padding: 8px 10px;
  border-radius: 10px;
  color: var(--text);
  transition: background 0.2s ease, color 0.2s ease;
}

.nav a:hover {
  background: rgba(0, 194, 255, 0.12);
  color: #fff;
}

.nav-toggle {
  display: none;
  background: none;
  border: 1px solid var(--border);
  color: var(--text);
  border-radius: 10px;
  padding: 6px 10px;
  font-size: 1.1rem;
}

.theme-toggle {
  border: 1px solid var(--border);
  background: rgba(255, 255, 255, 0.04);
  color: var(--text);
  border-radius: 10px;
  padding: 6px 10px;
  cursor: pointer;
  transition: background 0.2s ease, transform 0.1s ease, box-shadow 0.2s ease;
}

.theme-toggle:hover {
  background: rgba(0, 194, 255, 0.12);
  box-shadow: var(--shadow);
}

.theme-toggle:active {
  transform: translateY(1px);
}

.hero {
  display: grid;
  grid-template-columns: 1.2fr 0.8fr;
  gap: 30px;
  align-items: center;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 24px;
  padding: 30px;
  box-shadow: var(--shadow);
}

.hero-content h1 {
  font-size: clamp(2rem, 3vw, 2.8rem);
}

.eyebrow {
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--muted);
  font-size: 0.85rem;
  margin: 0 0 0.5rem;
}

.tagline {
  color: #d2e7ff;
  max-width: 640px;
  margin: 0 0 1rem;
}

.hero-logos img {
  width: 100%;
  border-radius: 18px;
  border: 1px solid var(--border);
  box-shadow: var(--shadow);
}

.hero-actions {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
}

.btn {
  display: inline-block;
  padding: 10px 16px;
  border-radius: 12px;
  border: 1px solid var(--border);
  color: var(--text);
  background: rgba(255, 255, 255, 0.02);
  transition: transform 0.1s ease, box-shadow 0.2s ease;
}

.btn.primary {
  background: var(--accent);
  color: #04101f;
  font-weight: 700;
  box-shadow: 0 10px 30px rgba(0, 194, 255, 0.35);
}

.btn:hover {
  transform: translateY(-1px);
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.3);
}

.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 22px;
  margin-top: 24px;
  box-shadow: var(--shadow);
}

.info-table {
  width: 100%;
  border-collapse: collapse;
  background: rgba(255, 255, 255, 0.01);
  border-radius: 12px;
  overflow: hidden;
}

.info-table th,
.info-table td {
  padding: 12px 14px;
  border-bottom: 1px solid var(--border);
  text-align: left;
}

.info-table th {
  color: #c6ddff;
  width: 22%;
}

.info-table tr:last-child th,
.info-table tr:last-child td {
  border-bottom: none;
}

.table-scroll {
  overflow-x: auto;
}

.schedule-table th,
.schedule-table td {
  width: auto;
}

.schedule-table tbody tr.lecture {
  background: linear-gradient(90deg, rgba(11, 116, 222, 0.22), transparent 45%);
}

.schedule-table tbody tr.lab {
  background: linear-gradient(90deg, rgba(5, 173, 94, 0.22), transparent 45%);
}

:root[data-theme="dark"] .schedule-table tbody tr.lecture {
  background: linear-gradient(90deg, rgba(0, 194, 255, 0.28), transparent 45%);
}

:root[data-theme="dark"] .schedule-table tbody tr.lab {
  background: linear-gradient(90deg, rgba(0, 255, 188, 0.28), transparent 45%);
}

ul {
  padding-left: 18px;
  margin: 0.5rem 0 0;
}

.columns {
  columns: 2;
  column-gap: 24px;
}

.instructor {
  display: flex;
  gap: 16px;
  align-items: center;
  margin-top: 12px;
}

.instructor img {
  width: 120px;
  height: 120px;
  border-radius: 14px;
  object-fit: cover;
  border: 1px solid var(--border);
  box-shadow: var(--shadow);
}

.book-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: 14px;
  margin-top: 14px;
}

.book-grid img {
  width: 100%;
  border-radius: 12px;
  border: 1px solid var(--border);
  box-shadow: var(--shadow);
  background: rgba(255, 255, 255, 0.02);
}

.note {
  color: var(--muted);
  margin-top: 10px;
}

.contact {
  text-align: center;
}

.footer {
  text-align: center;
  padding: 24px 12px 34px;
  color: var(--muted);
}

.footer a {
  margin-left: 10px;
}

@media (max-width: 900px) {
  .hero {
    grid-template-columns: 1fr;
  }

  .columns {
    columns: 1;
  }

  .nav ul {
    display: none;
    width: 100%;
    flex-direction: column;
    background: var(--header-bg);
    margin-top: 10px;
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 8px;
  }

  .nav ul.open {
    display: flex;
  }

  .nav-toggle {
    display: inline-block;
  }

  .nav {
    flex-wrap: wrap;
  }
}