:root {
  --bg: #f7f9fb;
  --surface: #ffffff;
  --surface-soft: #eef3f7;
  --text: #18202a;
  --muted: #667282;
  --line: #d9e1e8;
  --primary: #1f5f8f;
  --primary-dark: #174563;
  --accent: #b68a42;
  --shadow: 0 18px 50px rgba(24, 32, 42, 0.08);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: "Noto Serif SC", "Songti SC", "SimSun", serif;
  line-height: 1.7;
}

a {
  color: inherit;
  text-decoration: none;
}

.container {
  width: min(1120px, calc(100% - 40px));
  margin: 0 auto;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: rgba(255, 255, 255, 0.92);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(16px);
}

.header-inner {
  min-height: 72px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.brand {
  display: inline-flex;
  align-items: center;
  font-weight: 700;
  font-size: 20px;
}

.site-nav {
  display: flex;
  align-items: center;
  gap: 26px;
  color: var(--muted);
  font-size: 15px;
}

.site-nav a:hover {
  color: var(--primary);
}

.hero {
  padding: 86px 0 76px;
  background:
    linear-gradient(120deg, rgba(31, 95, 143, 0.10), transparent 42%),
    linear-gradient(180deg, #ffffff 0%, var(--bg) 100%);
}

.hero-grid {
  max-width: 760px;
}

.eyebrow,
.section-label {
  margin: 0 0 12px;
  color: var(--accent);
  font-family: "PingFang SC", "Microsoft YaHei", sans-serif;
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0;
  text-transform: uppercase;
}

h1,
h2,
h3,
p {
  margin-top: 0;
}

h1 {
  margin-bottom: 22px;
  font-size: clamp(42px, 6vw, 68px);
  line-height: 1.1;
  letter-spacing: 0;
}

h2 {
  margin-bottom: 18px;
  font-size: clamp(28px, 4vw, 42px);
  line-height: 1.18;
  letter-spacing: 0;
}

h3 {
  margin-bottom: 12px;
  font-size: 22px;
  line-height: 1.3;
}

.hero-text {
  max-width: 650px;
  color: var(--muted);
  font-size: 19px;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  margin-top: 34px;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 46px;
  padding: 0 22px;
  border: 1px solid transparent;
  border-radius: 6px;
  font-family: "PingFang SC", "Microsoft YaHei", sans-serif;
  font-size: 15px;
  font-weight: 600;
}

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

.btn-primary:hover {
  background: var(--primary-dark);
}

.btn-secondary {
  color: var(--primary);
  background: #fff;
  border-color: var(--line);
}

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

.section {
  padding: 76px 0;
}

.section-muted {
  background: var(--surface-soft);
}

.section-grid {
  display: grid;
  grid-template-columns: 300px minmax(0, 1fr);
  gap: 80px;
}

.section-content {
  color: var(--muted);
  font-size: 17px;
}

.section-heading {
  max-width: 680px;
  margin-bottom: 34px;
}

.course-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 20px;
}

.course-card {
  min-height: 240px;
  display: flex;
  flex-direction: column;
  padding: 28px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 8px;
  transition: transform 160ms ease, box-shadow 160ms ease, border-color 160ms ease;
}

.course-card:hover {
  transform: translateY(-4px);
  border-color: rgba(31, 95, 143, 0.34);
  box-shadow: var(--shadow);
}

.course-index {
  margin-bottom: 36px;
  color: var(--accent);
  font-family: Georgia, serif;
  font-size: 18px;
  font-weight: 700;
}

.course-card p {
  margin-bottom: 0;
  color: var(--muted);
}

.notice-section {
  background: #fff;
  border-top: 1px solid var(--line);
}

.notice-section p:last-child {
  max-width: 920px;
  color: var(--muted);
}

.site-footer {
  background: #18202a;
  color: rgba(255, 255, 255, 0.78);
  font-family: "PingFang SC", "Microsoft YaHei", sans-serif;
  font-size: 14px;
}

.footer-inner {
  min-height: 82px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
}

.site-footer a {
  color: rgba(255, 255, 255, 0.9);
}

.site-footer a:hover {
  color: #fff;
}

@media (max-width: 860px) {
  .header-inner,
  .footer-inner {
    align-items: flex-start;
    flex-direction: column;
    justify-content: center;
    padding: 16px 0;
  }

  .site-nav {
    width: 100%;
    flex-wrap: wrap;
    gap: 14px 20px;
  }

  .hero {
    padding: 58px 0;
  }

  .section-grid {
    grid-template-columns: 1fr;
    gap: 30px;
  }

  .course-grid {
    grid-template-columns: 1fr;
  }

  .section {
    padding: 56px 0;
  }
}

@media (max-width: 520px) {
  .container {
    width: min(100% - 28px, 1120px);
  }

  .brand {
    font-size: 18px;
  }

  .hero-actions {
    display: grid;
  }

  .btn {
    width: 100%;
  }

  .course-card {
    padding: 22px;
  }
}