:root {
  --bg: #f4f7fb;
  --card: #ffffff;
  --ink: #152033;
  --muted: #5b6b7c;
  --line: #d9e2ec;
  --accent: #3b6ff5;
  --accent-2: #1f4fd8;
}
* { box-sizing: border-box; }
html, body {
  margin: 0;
  padding: 0;
  font-family: "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  color: var(--ink);
  background:
    radial-gradient(900px 420px at 12% -10%, #dfeaff 0%, transparent 55%),
    radial-gradient(700px 380px at 90% 0%, #eef2ff 0%, transparent 50%),
    var(--bg);
}
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }
.wrap { width: min(980px, calc(100% - 32px)); margin: 0 auto; }
.top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 18px 0;
  border-bottom: 1px solid var(--line);
  margin-bottom: 28px;
}
.brand {
  font-weight: 700;
  font-size: 18px;
  color: var(--ink);
  letter-spacing: 0.2px;
}
.nav { display: flex; gap: 16px; flex-wrap: wrap; font-size: 14px; }
.nav a { color: var(--muted); }
.hero {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 18px;
  padding: 34px 28px;
  margin-bottom: 22px;
}
.hero h1 {
  margin: 0 0 12px;
  font-size: clamp(28px, 4vw, 40px);
  line-height: 1.2;
}
.hero p {
  margin: 0;
  color: var(--muted);
  font-size: 16px;
  line-height: 1.7;
  max-width: 46rem;
}
.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 14px;
  margin: 18px 0 28px;
}
.card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 18px 16px;
}
.card h3 { margin: 0 0 8px; font-size: 17px; }
.card p { margin: 0; color: var(--muted); font-size: 14px; line-height: 1.65; }
.section {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 24px 22px;
  margin-bottom: 18px;
}
.section h2 { margin: 0 0 12px; font-size: 22px; }
.section p, .section li {
  color: var(--muted);
  line-height: 1.75;
  font-size: 15px;
}
.section ol { padding-left: 1.2rem; }
.note {
  margin-top: 14px;
  padding: 12px 14px;
  border-radius: 10px;
  background: #eef4ff;
  color: #274690;
  font-size: 14px;
}
.footer {
  margin: 28px 0 40px;
  color: var(--muted);
  font-size: 13px;
  display: flex;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
  border-top: 1px solid var(--line);
  padding-top: 16px;
}
@media (max-width: 640px) {
  .hero { padding: 24px 18px; }
  .section { padding: 18px 16px; }
}