:root {
  --ink: #14213d;
  --ink-2: #2b3a5c;
  --muted: #5d6b85;
  --line: #e3e8f0;
  --bg: #f7f9fc;
  --card: #ffffff;
  --brand: #1f3864;
  --accent: #2e75b6;
  --warn: #d97706;
  --radius: 14px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: "Microsoft YaHei", "PingFang SC", "Noto Sans SC", system-ui, sans-serif;
  color: var(--ink);
  background: var(--bg);
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
}

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

.wrap { max-width: 1080px; margin: 0 auto; padding: 0 22px; }

/* 顶部 */
.topbar {
  position: sticky; top: 0; z-index: 20;
  background: rgba(247, 249, 252, .92);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--line);
}
.topbar .wrap { display: flex; align-items: center; justify-content: space-between; height: 64px; }
.logo { font-weight: 800; font-size: 19px; color: var(--brand); letter-spacing: .5px; }
.logo span { color: var(--accent); }
.nav a { margin-left: 20px; color: var(--ink-2); font-size: 14px; }

/* 首屏 */
.hero { padding: 72px 0 40px; }
.hero h1 {
  font-size: clamp(30px, 5vw, 48px);
  line-height: 1.25;
  margin: 0 0 16px;
  letter-spacing: -1px;
}
.hero h1 em { font-style: normal; color: var(--accent); }
.hero p { font-size: 17px; color: var(--muted); max-width: 640px; margin: 0 0 26px; }

.buttons { display: flex; gap: 12px; flex-wrap: wrap; }
.btn {
  display: inline-block; padding: 12px 22px; border-radius: 999px;
  font-weight: 700; font-size: 15px; border: 1px solid transparent;
}
.btn-primary { background: var(--brand); color: #fff; }
.btn-primary:hover { background: #16294a; text-decoration: none; }
.btn-ghost { border-color: var(--line); color: var(--ink-2); background: #fff; }
.btn-ghost:hover { border-color: var(--accent); text-decoration: none; }

/* 卡片区 */
.section { padding: 34px 0; }
.section-head { display: flex; align-items: baseline; justify-content: space-between; margin-bottom: 18px; }
.section-head h2 { font-size: 22px; margin: 0; }
.section-head span { color: var(--muted); font-size: 13px; }

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

.card {
  background: var(--card); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 20px; display: flex; flex-direction: column; gap: 10px;
  transition: transform .15s ease, box-shadow .15s ease;
}
.card:hover { transform: translateY(-3px); box-shadow: 0 12px 30px rgba(20, 33, 61, .08); }
.card .tag {
  align-self: flex-start; font-size: 12px; font-weight: 700; color: var(--warn);
  background: #fff7ed; border: 1px solid #fed7aa; padding: 2px 10px; border-radius: 999px;
}
.card h3 { margin: 0; font-size: 18px; }
.card p { margin: 0; color: var(--muted); font-size: 14px; }
.card .meta { margin-top: auto; font-size: 12px; color: #8a97ad; display: flex; gap: 12px; }

/* 文章页 */
.article { background: #fff; padding: 40px 0 60px; }
.article .wrap { max-width: 780px; }
.crumb { font-size: 13px; color: var(--muted); margin-bottom: 18px; }
.article h1 { font-size: clamp(26px, 4vw, 38px); line-height: 1.3; margin: 0 0 14px; }
.article .lead { font-size: 17px; color: var(--ink-2); margin: 0 0 22px; }
.article h2 { font-size: 22px; margin: 38px 0 12px; padding-top: 8px; border-top: 1px solid var(--line); }
.article h3 { font-size: 17px; margin: 26px 0 8px; }
.article ul, .article ol { padding-left: 22px; }
.article li { margin: 6px 0; }
.article code { background: #eef3fa; padding: 2px 6px; border-radius: 5px; font-size: 90%; }
.article table { width: 100%; border-collapse: collapse; margin: 16px 0; font-size: 14px; }
.article th, .article td { border: 1px solid var(--line); padding: 10px 12px; text-align: left; }
.article th { background: #eef3fa; }

.callout {
  background: #eef4fb; border-left: 4px solid var(--accent);
  padding: 14px 18px; border-radius: 0 10px 10px 0; margin: 20px 0; font-size: 15px;
}

.affiliate {
  border: 1px dashed #c7d4e8; border-radius: 12px; padding: 16px 18px; margin: 26px 0;
  background: #fbfdff; font-size: 14px; color: var(--muted);
}
.affiliate strong { color: var(--ink); }

.cta {
  background: var(--brand); color: #fff; border-radius: var(--radius);
  padding: 26px; margin: 34px 0; text-align: center;
}
.cta h3 { margin: 0 0 8px; font-size: 20px; }
.cta p { margin: 0 0 16px; color: #c9d6ea; font-size: 14px; }
.cta a { background: #fff; color: var(--brand); padding: 10px 20px; border-radius: 999px; font-weight: 700; display: inline-block; }

.related { margin-top: 40px; }
.related h3 { font-size: 16px; color: var(--muted); }

/* 页脚 */
footer { border-top: 1px solid var(--line); padding: 30px 0 50px; color: var(--muted); font-size: 13px; }
footer .wrap { display: flex; justify-content: space-between; gap: 20px; flex-wrap: wrap; }
footer a { color: var(--muted); }

@media (max-width: 640px) {
  .nav { display: none; }
  .hero { padding: 48px 0 24px; }
  .article { padding: 26px 0 40px; }
}