:root {
  --primary: #1a56db;
  --primary-dark: #1e429f;
  --bg: #f7f9fc;
  --text: #1f2937;
  --text-light: #5b6572;
  --border: #e3e8ef;
  --radius: 12px;
}

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

body {
  font-family: "PingFang SC", "Microsoft YaHei", "Hiragino Sans GB", system-ui, -apple-system, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.75;
  font-size: 16px;
}

a { color: var(--primary); text-decoration: none; }
a:hover { text-decoration: underline; }

.wrap { max-width: 1080px; margin: 0 auto; padding: 0 24px; }

/* 顶部导航 */
header {
  background: #fff;
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 10;
}
header .wrap {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}
.brand {
  font-size: 18px;
  font-weight: 700;
  color: var(--text);
  letter-spacing: .5px;
}
.brand:hover { text-decoration: none; color: var(--primary); }
nav a {
  color: var(--text-light);
  margin-left: 28px;
  font-size: 15px;
}
nav a:hover, nav a.active { color: var(--primary); text-decoration: none; }

/* 首屏 */
.hero {
  background: linear-gradient(180deg, #eef4ff 0%, var(--bg) 100%);
  padding: 72px 0 56px;
  text-align: center;
}
.hero h1 {
  font-size: 34px;
  letter-spacing: 1px;
  margin-bottom: 14px;
}
.hero .sub {
  font-size: 17px;
  color: var(--text-light);
  margin-bottom: 8px;
}
.hero .desc {
  max-width: 640px;
  margin: 18px auto 0;
  color: var(--text-light);
  font-size: 15px;
}

main { padding-bottom: 64px; }

/* 卡片 */
.cards {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
  margin-top: 40px;
}
.card {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px 26px;
  transition: box-shadow .2s, transform .2s;
  display: block;
  color: var(--text);
}
.card:hover {
  box-shadow: 0 8px 24px rgba(26, 86, 219, .1);
  transform: translateY(-2px);
  text-decoration: none;
}
.card h3 { font-size: 18px; margin-bottom: 10px; color: var(--primary); }
.card p { font-size: 14px; color: var(--text-light); }

/* 内容页 */
.page {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 40px 44px;
  margin-top: 40px;
}
.page h1 {
  font-size: 26px;
  margin-bottom: 8px;
}
.page .lead {
  color: var(--text-light);
  font-size: 15px;
  border-left: 3px solid var(--primary);
  padding-left: 14px;
  margin: 18px 0 28px;
}
.page h2 {
  font-size: 19px;
  margin: 32px 0 14px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border);
}
.page p { margin: 10px 0; font-size: 15px; }
.page ul, .page ol { margin: 10px 0 10px 24px; font-size: 15px; }
.page li { margin: 6px 0; }

.cat {
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 16px 20px;
  margin: 12px 0;
  background: #fbfcfe;
}
.cat h3 { font-size: 16px; margin-bottom: 6px; }
.cat p { font-size: 14px; color: var(--text-light); margin: 0; }

table {
  width: 100%;
  border-collapse: collapse;
  margin: 16px 0;
  font-size: 14px;
}
th, td {
  border: 1px solid var(--border);
  padding: 10px 14px;
  text-align: left;
}
th { background: #f2f6fd; font-weight: 600; }

/* 页脚 */
footer {
  border-top: 1px solid var(--border);
  background: #fff;
  padding: 28px 0;
  text-align: center;
  color: var(--text-light);
  font-size: 13px;
}
footer p { margin: 6px 0; }
footer a { color: var(--text-light); }
footer a:hover { color: var(--primary); }

@media (max-width: 760px) {
  .cards { grid-template-columns: 1fr; }
  header .wrap { flex-direction: column; height: auto; padding: 12px 24px; gap: 8px; }
  nav a { margin: 0 10px; }
  .hero { padding: 48px 0 36px; }
  .hero h1 { font-size: 26px; }
  .page { padding: 26px 22px; }
}