:root {
  --bg: #f6f7f9;
  --card: #ffffff;
  --text: #1f2937;
  --muted: #6b7280;
  --primary: #1a56db;
  --primary-dark: #12409f;
  --accent: #e11d48;
  --warn-bg: #fef3c7;
  --warn-text: #92400e;
  --border: #e5e7eb;
  --green: #059669;
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  font-size: 16px;
}

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

.container { max-width: 960px; margin: 0 auto; padding: 0 20px; }

/* 顶部导航 */
.nav {
  background: var(--card);
  border-bottom: 1px solid var(--border);
  position: sticky; top: 0; z-index: 10;
}
.nav-inner {
  max-width: 960px; margin: 0 auto; padding: 12px 20px;
  display: flex; align-items: center; justify-content: space-between;
}
.nav .logo { font-size: 18px; font-weight: 700; color: var(--text); }
.nav .logo span { color: var(--primary); }
.nav-links { display: flex; gap: 18px; font-size: 14px; }
.nav-links a { color: var(--muted); }
.nav-links a:hover { color: var(--primary); text-decoration: none; }
.nav .btn-cta {
  background: var(--primary); color: #fff; padding: 8px 16px;
  border-radius: 6px; font-size: 14px; font-weight: 600;
}
.nav .btn-cta:hover { background: var(--primary-dark); text-decoration: none; }

/* Hero */
.hero {
  background: linear-gradient(135deg, #1a56db 0%, #3b82f6 100%);
  color: #fff; padding: 64px 0 56px;
}
.hero h1 { font-size: 34px; line-height: 1.3; margin-bottom: 16px; }
.hero p { font-size: 17px; opacity: .92; max-width: 640px; margin-bottom: 28px; }
.hero .btn-main {
  display: inline-block; background: #fff; color: var(--primary);
  padding: 14px 32px; border-radius: 8px; font-size: 16px; font-weight: 700;
}
.hero .btn-main:hover { text-decoration: none; transform: translateY(-1px); }
.hero .hero-note { margin-top: 16px; font-size: 13px; opacity: .8; }

/* 区块 */
.section { padding: 48px 0; }
.section h2 { font-size: 24px; margin-bottom: 8px; }
.section .lead { color: var(--muted); margin-bottom: 28px; }

/* 核心账本卡片 */
.formula-card {
  background: var(--card); border: 2px solid var(--primary);
  border-radius: 12px; padding: 28px; text-align: center;
  margin-bottom: 28px;
}
.formula-card .formula {
  font-size: 26px; font-weight: 700; color: var(--primary);
  margin: 12px 0;
}
.formula-card .formula .op { color: var(--accent); }

/* 场景卡片网格 */
.grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; }
.card {
  background: var(--card); border: 1px solid var(--border);
  border-radius: 10px; padding: 20px; display: block; color: var(--text);
  transition: box-shadow .15s, transform .15s;
}
.card:hover { box-shadow: 0 6px 20px rgba(0,0,0,.08); transform: translateY(-2px); text-decoration: none; }
.card .card-title { font-size: 17px; font-weight: 700; margin-bottom: 6px; }
.card .card-desc { font-size: 14px; color: var(--muted); }
.card .card-tag { color: var(--primary); font-size: 13px; font-weight: 600; }

/* 铁律列表 */
.rule-list { list-style: none; }
.rule-list li {
  background: var(--card); border: 1px solid var(--border);
  border-radius: 8px; padding: 14px 18px; margin-bottom: 10px;
}
.rule-list li strong { color: var(--primary); }

/* 内容页 */
.article { background: var(--card); border-radius: 12px; padding: 40px; }
.article h1 { font-size: 28px; line-height: 1.35; margin-bottom: 12px; }
.article h2 { font-size: 20px; margin: 32px 0 12px; padding-top: 20px; border-top: 1px solid var(--border); }
.article h3 { font-size: 17px; margin: 20px 0 8px; }
.article p { margin-bottom: 12px; }
.article ul, .article ol { padding-left: 22px; margin-bottom: 14px; }
.article li { margin-bottom: 6px; }

.breadcrumb { font-size: 14px; color: var(--muted); margin-bottom: 16px; }
.breadcrumb a { color: var(--muted); }

/* 引用块（话术） */
.quote {
  background: #eef2ff; border-left: 4px solid var(--primary);
  padding: 14px 18px; border-radius: 0 8px 8px 0; margin: 14px 0;
  font-size: 15px;
}

/* 警示框 */
.warn {
  background: var(--warn-bg); color: var(--warn-text);
  border-left: 4px solid #f59e0b; padding: 14px 18px;
  border-radius: 0 8px 8px 0; margin: 16px 0; font-size: 14px;
}
.warn strong { display: block; margin-bottom: 4px; }

/* 表格 */
table { width: 100%; border-collapse: collapse; margin: 16px 0; font-size: 14px; }
th, td { border: 1px solid var(--border); padding: 10px 12px; text-align: left; }
th { background: #f3f4f6; font-weight: 600; }

/* 免责 footer */
.disclaimer {
  background: #fef2f2; border: 1px solid #fecaca; color: #991b1b;
  border-radius: 10px; padding: 18px; font-size: 13px; margin-top: 28px;
}

.site-footer {
  background: var(--card); border-top: 1px solid var(--border);
  padding: 28px 0; margin-top: 48px; font-size: 13px; color: var(--muted);
}
.site-footer .container { text-align: center; }

/* 自测工具 */
.form-group { margin-bottom: 20px; }
.form-group label { display: block; font-weight: 600; margin-bottom: 8px; }
.form-group select, .form-group input {
  width: 100%; padding: 12px 14px; border: 1px solid var(--border);
  border-radius: 8px; font-size: 15px; background: #fff;
}
.form-group .hint { font-size: 13px; color: var(--muted); margin-top: 6px; }
.btn-submit {
  width: 100%; background: var(--primary); color: #fff;
  border: none; padding: 14px; border-radius: 8px; font-size: 16px;
  font-weight: 700; cursor: pointer;
}
.btn-submit:hover { background: var(--primary-dark); }

.result-box {
  background: #ecfdf5; border: 1px solid #a7f3d0; border-radius: 10px;
  padding: 20px; margin-top: 24px; display: none;
}
.result-box.show { display: block; }
.result-box h3 { color: var(--green); margin-bottom: 8px; }
.result-box.warn-level { background: var(--warn-bg); border-color: #fcd34d; }
.result-box.warn-level h3 { color: var(--warn-text); }
.result-box.risk-level { background: #fef2f2; border-color: #fecaca; }
.result-box.risk-level h3 { color: #991b1b; }

.tag { display: inline-block; padding: 2px 10px; border-radius: 20px; font-size: 12px; font-weight: 600; }
.tag-blue { background: #dbeafe; color: #1e40af; }
.tag-green { background: #d1fae5; color: #065f46; }
.tag-red { background: #fee2e2; color: #991b1b; }

@media (max-width: 720px) {
  .grid { grid-template-columns: 1fr; }
  .hero { padding: 40px 0 32px; }
  .hero h1 { font-size: 24px; }
  .hero p { font-size: 15px; }
  .hero .btn-main { padding: 12px 24px; font-size: 15px; }
  .article { padding: 20px; }
  .article h1 { font-size: 22px; }
  .article h2 { font-size: 18px; }
  .nav-links { display: none; }
  .nav .logo { font-size: 16px; }
  .nav .btn-cta { padding: 6px 12px; font-size: 13px; }
  .nav-inner { padding: 10px 16px; }
  .formula-card { padding: 20px 16px; }
  .formula-card .formula { font-size: 20px; }
  .section { padding: 32px 0; }
  .section h2 { font-size: 20px; }
  .rule-list li { padding: 12px 14px; }
  .container { padding: 0 16px; }

  /* 表格横向滚动，避免在手机上溢出 */
  table { display: block; overflow-x: auto; white-space: nowrap; -webkit-overflow-scrolling: touch; }

  /* 面包屑与正文间距微调 */
  .breadcrumb { font-size: 13px; }
  .quote { font-size: 14px; }
  .warn { font-size: 13px; }
  .form-group select, .form-group input { font-size: 16px; }
}

@media (max-width: 380px) {
  .hero h1 { font-size: 21px; }
  .formula-card .formula { font-size: 17px; }
}