:root {
  --bg: #07111f;
  --bg-soft: rgba(18, 31, 52, 0.78);
  --panel: rgba(12, 24, 42, 0.9);
  --panel-border: rgba(122, 162, 247, 0.16);
  --text: #e8eefc;
  --muted: #93a4c7;
  --accent: #78a6ff;
  --accent-2: #67e8f9;
  --success: #7ef0c0;
  --shadow: 0 18px 50px rgba(0, 0, 0, 0.28);
  --radius: 22px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: Inter, "PingFang SC", "Microsoft YaHei", sans-serif;
  color: var(--text);
  background:
    radial-gradient(circle at top left, rgba(120, 166, 255, 0.18), transparent 30%),
    radial-gradient(circle at top right, rgba(103, 232, 249, 0.12), transparent 25%),
    linear-gradient(180deg, #08111f 0%, #091728 100%);
  min-height: 100vh;
}

.bg-grid {
  position: fixed;
  inset: 0;
  background-image:
    linear-gradient(rgba(255,255,255,0.04) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255,255,255,0.04) 1px, transparent 1px);
  background-size: 36px 36px;
  mask-image: linear-gradient(180deg, rgba(255,255,255,0.55), transparent 85%);
  pointer-events: none;
}

.hero,
.section,
.footer {
  position: relative;
  z-index: 1;
}

.hero {
  padding: 24px clamp(20px, 5vw, 64px) 54px;
}

.top-nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 20px;
  padding: 14px 18px;
  background: rgba(6, 14, 26, 0.6);
  backdrop-filter: blur(16px);
  border: 1px solid rgba(255,255,255,0.08);
  border-radius: 18px;
}

.brand {
  font-size: 1rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.nav-links {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
}

.nav-links a,
.footer a {
  color: var(--muted);
  text-decoration: none;
}

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

.hero-content {
  max-width: 1120px;
  margin: 52px auto 0;
}

.eyebrow,
.section-kicker {
  text-transform: uppercase;
  letter-spacing: 0.16em;
  color: var(--accent-2);
  font-size: 0.82rem;
  margin: 0 0 12px;
}

h1 {
  margin: 0;
  font-size: clamp(2.5rem, 6vw, 5rem);
  line-height: 1.04;
  max-width: 10ch;
}

.hero-copy,
.section-head p {
  color: var(--muted);
  font-size: 1.04rem;
  line-height: 1.8;
  max-width: 760px;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  margin-top: 28px;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 14px 20px;
  border-radius: 999px;
  text-decoration: none;
  font-weight: 700;
  border: 1px solid transparent;
}

.btn.primary {
  color: #07111f;
  background: linear-gradient(135deg, var(--accent-2), var(--accent));
}

.btn.secondary {
  color: var(--text);
  border-color: rgba(255,255,255,0.16);
  background: rgba(255,255,255,0.03);
}

.hero-stats,
.overview-grid,
.method-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 18px;
  margin-top: 34px;
}

.stat-card,
.overview-card,
.method-card,
.day-card,
.topic-card {
  background: var(--panel);
  border: 1px solid var(--panel-border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.stat-card {
  padding: 20px;
}

.stat-card span {
  display: block;
  font-size: 2rem;
  font-weight: 800;
  color: var(--success);
}

.stat-card small {
  color: var(--muted);
}

.section {
  padding: 24px clamp(20px, 5vw, 64px) 14px;
}

.section.alt {
  background: rgba(255,255,255,0.02);
}

.section-head {
  max-width: 1120px;
  margin: 0 auto 22px;
}

.overview-grid,
.schedule-grid,
.topic-groups,
.method-grid {
  max-width: 1120px;
  margin-left: auto;
  margin-right: auto;
}

.overview-card,
.method-card,
.topic-card {
  padding: 24px;
}

.overview-card h3,
.method-card h3,
.topic-card h3,
.day-card h3 {
  margin-top: 0;
}

.overview-card ul,
.topic-card ul,
.day-card ul {
  margin: 0;
  padding-left: 20px;
  color: var(--muted);
  line-height: 1.8;
}

.schedule-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 18px;
}

.day-card {
  padding: 22px;
}

.day-badge {
  display: inline-flex;
  padding: 6px 12px;
  border-radius: 999px;
  background: rgba(120, 166, 255, 0.14);
  color: var(--accent-2);
  font-size: 0.85rem;
  margin-bottom: 14px;
}

.day-card p {
  color: var(--muted);
  line-height: 1.75;
}

.day-block {
  margin-top: 14px;
  padding-top: 14px;
  border-top: 1px solid rgba(255,255,255,0.08);
}

.day-block strong {
  display: block;
  margin-bottom: 8px;
  color: var(--text);
}

.topic-groups {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 18px;
}

.footer {
  padding: 30px 20px 60px;
  text-align: center;
  color: var(--muted);
}

code {
  padding: 0.15em 0.4em;
  border-radius: 8px;
  background: rgba(255,255,255,0.06);
}

@media (max-width: 720px) {
  .top-nav {
    flex-direction: column;
    align-items: flex-start;
  }

  h1 {
    max-width: none;
  }

  .hero {
    padding-top: 16px;
  }
}