:root {
  --bg: #ffffff;
  --bg-soft: #f8fafc;
  --text: #0f172a;
  --muted: #64748b;
  --line: #e2e8f0;
  --line-strong: #cbd5e1;
  --accent: #2563eb;
  --accent-soft: #eff6ff;
  --radius: 16px;
  --font: "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", system-ui, -apple-system, sans-serif;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font);
  color: var(--text);
  background: var(--bg);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

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

.container {
  width: min(1080px, 100% - 40px);
  margin: 0 auto;
}

/* header */
.header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: rgba(255, 255, 255, 0.9);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--line);
}

.header-inner {
  height: 64px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 16px;
  font-weight: 700;
}

.brand img {
  width: 34px;
  height: 34px;
  border-radius: 9px;
  object-fit: cover;
}

.nav {
  display: flex;
  gap: 28px;
}

.nav a {
  font-size: 14px;
  color: var(--muted);
  transition: color 0.2s ease;
}

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

/* hero */
.hero {
  padding: 110px 0 90px;
  text-align: center;
}

.hero h1 {
  font-size: clamp(38px, 6vw, 56px);
  font-weight: 800;
  letter-spacing: -0.5px;
}

.hero h1 span {
  color: var(--accent);
}

.hero p {
  max-width: 560px;
  margin: 18px auto 0;
  font-size: 16px;
  color: var(--muted);
}

.hero-cta {
  display: inline-block;
  margin-top: 32px;
  padding: 11px 28px;
  border-radius: 999px;
  font-size: 14px;
  font-weight: 600;
  color: #ffffff;
  background: var(--accent);
  transition: background 0.2s ease, transform 0.2s ease;
}

.hero-cta:hover {
  background: #1d4ed8;
  transform: translateY(-1px);
}

/* sections */
.section {
  padding: 64px 0;
}

.section-title {
  font-size: 22px;
  font-weight: 700;
  text-align: center;
  margin-bottom: 36px;
}

/* module cards */
.module-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

.module-card {
  display: flex;
  flex-direction: column;
  padding: 30px 26px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--bg);
  transition: border-color 0.2s ease, box-shadow 0.2s ease, transform 0.2s ease;
}

.module-card:hover {
  border-color: var(--line-strong);
  box-shadow: 0 12px 28px rgba(15, 23, 42, 0.08);
  transform: translateY(-3px);
}

.module-card .icon {
  width: 46px;
  height: 46px;
  border-radius: 12px;
  display: grid;
  place-items: center;
  background: var(--accent-soft);
  margin-bottom: 20px;
}

.module-card .icon svg {
  width: 24px;
  height: 24px;
  stroke: var(--accent);
}

.module-card h3 {
  font-size: 20px;
  font-weight: 700;
  margin-bottom: 8px;
}

.module-card p {
  font-size: 14.5px;
  color: var(--muted);
  flex: 1;
}

.module-card .more {
  margin-top: 18px;
  font-size: 14px;
  font-weight: 600;
  color: var(--accent);
}

/* module detail sections */
.detail {
  border-top: 1px solid var(--line);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 32px;
  scroll-margin-top: 80px;
}

.detail-head .num {
  font-size: 13px;
  font-weight: 600;
  color: var(--accent);
  letter-spacing: 2px;
}

.detail-head h3 {
  font-size: 26px;
  font-weight: 700;
  margin: 6px 0 10px;
}

.detail-head p {
  max-width: 560px;
  font-size: 15px;
  color: var(--muted);
}

.chips {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  justify-content: flex-end;
  flex-shrink: 0;
}

.chips span {
  padding: 7px 16px;
  border-radius: 999px;
  font-size: 13px;
  color: var(--muted);
  background: var(--bg-soft);
  border: 1px solid var(--line);
}

/* about */
.about {
  border-top: 1px solid var(--line);
  text-align: center;
}

.about p {
  max-width: 620px;
  margin: 0 auto;
  font-size: 15px;
  color: var(--muted);
}

/* footer */
.footer {
  border-top: 1px solid var(--line);
  padding: 28px 0;
  text-align: center;
}

.footer p {
  font-size: 13px;
  color: var(--muted);
}

@media (max-width: 820px) {
  .module-grid {
    grid-template-columns: 1fr;
    max-width: 480px;
    margin: 0 auto;
  }

  .detail {
    flex-direction: column;
    align-items: flex-start;
    gap: 16px;
  }

  .chips {
    justify-content: flex-start;
  }

  .nav {
    gap: 16px;
  }
}