:root {
  --bg: #f7f9fc;
  --text: #1b2330;
  --muted: #5b6678;
  --brand: #4fc3f7;
  --brand-dark: #1e88e5;
  --card: #ffffff;
  --border: #e4e9f0;
  --max: 960px;
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  background: var(--bg);
  color: var(--text);
  font: 16px/1.7 -apple-system, BlinkMacSystemFont, "PingFang SC",
    "Helvetica Neue", "Microsoft YaHei", sans-serif;
  -webkit-font-smoothing: antialiased;
}

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

.container {
  max-width: var(--max);
  margin: 0 auto;
  padding: 0 24px;
}

header.site {
  padding: 18px 0;
  border-bottom: 1px solid var(--border);
  background: #fff;
}
header.site .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 600;
  font-size: 18px;
  color: var(--text);
}
.logo-mark {
  width: 32px;
  height: 32px;
  border-radius: 8px;
  display: inline-block;
  vertical-align: middle;
  object-fit: contain;
}
.hero-icon {
  display: block;
  width: 104px;
  height: 104px;
  margin: 0 auto 22px;
  border-radius: 22px;
  box-shadow: 0 10px 30px rgba(30, 136, 229, 0.25);
}
nav.site a {
  margin-left: 22px;
  color: var(--muted);
  font-size: 14px;
}
nav.site a:hover { color: var(--text); text-decoration: none; }

.hero {
  padding: 72px 0 60px;
  text-align: center;
  background: linear-gradient(180deg, #fff 0%, var(--bg) 100%);
}
.hero h1 {
  font-size: 40px;
  line-height: 1.25;
  margin: 0 0 14px;
  letter-spacing: -0.5px;
}
.hero p.lead {
  font-size: 17px;
  color: var(--muted);
  max-width: 620px;
  margin: 0 auto 28px;
}
.btn {
  display: inline-block;
  padding: 12px 22px;
  background: var(--brand-dark);
  color: #fff;
  border-radius: 10px;
  font-weight: 500;
  font-size: 15px;
}
.btn:hover { background: #1976d2; text-decoration: none; }
.btn.ghost {
  background: #fff;
  color: var(--brand-dark);
  border: 1px solid var(--border);
  margin-left: 10px;
}
.btn.ghost:hover { background: #f2f6fb; }

section { padding: 56px 0; }
section h2 {
  font-size: 26px;
  margin: 0 0 12px;
  letter-spacing: -0.3px;
}
section .section-lead {
  color: var(--muted);
  margin-bottom: 36px;
}

.features {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 18px;
}
.feature {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 22px;
}
.feature h3 {
  margin: 6px 0 8px;
  font-size: 16px;
}
.feature p {
  margin: 0;
  color: var(--muted);
  font-size: 14px;
}
.feature .emoji {
  font-size: 22px;
  display: inline-block;
  width: 38px;
  height: 38px;
  border-radius: 10px;
  background: #e9f4fd;
  line-height: 38px;
  text-align: center;
}

footer.site {
  border-top: 1px solid var(--border);
  padding: 28px 0 40px;
  color: var(--muted);
  font-size: 13px;
  background: #fff;
}
footer.site .container {
  display: flex;
  flex-wrap: wrap;
  gap: 18px;
  justify-content: space-between;
  align-items: center;
}
footer.site a { color: var(--muted); margin-right: 14px; }
footer.site a:hover { color: var(--text); text-decoration: none; }

/* 正文页（隐私、条款、支持） */
.doc {
  background: #fff;
  padding: 48px 0 72px;
  border-bottom: 1px solid var(--border);
}
.doc h1 {
  font-size: 30px;
  letter-spacing: -0.5px;
  margin: 0 0 6px;
}
.doc .meta {
  color: var(--muted);
  font-size: 13px;
  margin-bottom: 32px;
}
.doc h2 {
  margin: 32px 0 10px;
  font-size: 19px;
}
.doc h3 {
  margin: 22px 0 8px;
  font-size: 16px;
}
.doc p, .doc li { color: #2a3544; }
.doc ul { padding-left: 22px; }
.doc code {
  background: #f2f4f8;
  padding: 1px 6px;
  border-radius: 4px;
  font-size: 13px;
}
.callout {
  background: #eef8ff;
  border-left: 3px solid var(--brand-dark);
  padding: 14px 16px;
  border-radius: 6px;
  color: #1b2330;
  margin: 16px 0;
}

@media (max-width: 560px) {
  .hero { padding: 48px 0 40px; }
  .hero h1 { font-size: 30px; }
  section { padding: 40px 0; }
  nav.site a { margin-left: 12px; font-size: 13px; }
}