/* ==========================================================================
   客服宝 kefubao.net.cn — 设计系统
   纯 CSS，无外部依赖；移动优先，响应式
   ========================================================================== */

:root {
  /* 品牌主色 */
  --blue-50:  #eef4ff;
  --blue-100: #dbe8ff;
  --blue-200: #b9d0ff;
  --blue-300: #8db2ff;
  --blue-500: #165dff;
  --blue-600: #0e46d4;
  --blue-700: #0a35a8;
  --blue-900: #071f66;

  /* 强调色 */
  --orange-50:  #fff5eb;
  --orange-100: #ffe4c7;
  --orange-500: #ff7d00;
  --orange-600: #e56a00;

  /* 功能色 */
  --green-50:  #e8ffea;
  --green-500: #00b42a;
  --red-500:   #f53f3f;

  /* 中性色 */
  --ink-900: #111827;
  --ink-800: #1d2129;
  --ink-600: #4e5969;
  --ink-500: #6b7280;
  --ink-400: #86909c;
  --ink-300: #c9cdd4;
  --ink-200: #e5e6eb;
  --ink-100: #f2f3f5;
  --ink-50:  #f7f8fa;
  --white:   #ffffff;

  /* 语义化 */
  --bg:            var(--white);
  --bg-soft:       var(--ink-50);
  --text:          var(--ink-800);
  --text-strong:   var(--ink-900);
  --text-muted:    var(--ink-600);
  --text-faint:    var(--ink-400);
  --border:        var(--ink-200);
  --border-soft:   var(--ink-100);
  --brand:         var(--blue-500);
  --brand-dark:    var(--blue-600);
  --accent:        var(--orange-500);

  /* 排版 */
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
               "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Consolas, "Liberation Mono", monospace;

  /* 尺寸 */
  --container: 1160px;
  --container-narrow: 820px;
  --radius-sm: 6px;
  --radius:    10px;
  --radius-lg: 16px;
  --radius-xl: 24px;

  /* 阴影 */
  --shadow-xs: 0 1px 2px rgba(17, 24, 39, .05);
  --shadow-sm: 0 2px 8px rgba(17, 24, 39, .06);
  --shadow:    0 8px 24px rgba(17, 24, 39, .08);
  --shadow-lg: 0 16px 48px rgba(17, 24, 39, .12);
  --shadow-brand: 0 8px 24px rgba(22, 93, 255, .22);

  /* 动效 */
  --ease: cubic-bezier(.4, 0, .2, 1);
}

/* ---------- Reset ---------- */
*, *::before, *::after { box-sizing: border-box; }

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: 84px;
}

body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.75;
  color: var(--text);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
}

h1, h2, h3, h4, h5, h6 {
  margin: 0 0 .6em;
  color: var(--text-strong);
  font-weight: 700;
  line-height: 1.3;
  letter-spacing: -.01em;
}

h1 { font-size: clamp(1.75rem, 4.4vw, 2.75rem); line-height: 1.22; text-wrap: balance; word-break: auto-phrase; }
h2 { font-size: clamp(1.375rem, 2.9vw, 1.875rem); text-wrap: balance; word-break: auto-phrase; }
h3 { font-size: clamp(1.125rem, 2vw, 1.3125rem); }
h4 { font-size: 1.0625rem; }

/* 锚点定位时避开吸顶导航 */
h1, h2, h3, h4 { scroll-margin-top: 90px; }

p { margin: 0 0 1em; }
p:last-child { margin-bottom: 0; }

a { color: var(--brand); text-decoration: none; transition: color .18s var(--ease); }
a:hover { color: var(--brand-dark); }

img, svg, video { max-width: 100%; height: auto; display: block; }
ul, ol { margin: 0 0 1em; padding-left: 1.35em; }
li { margin-bottom: .45em; }
li:last-child { margin-bottom: 0; }

strong, b { font-weight: 700; color: var(--text-strong); }
hr { border: 0; border-top: 1px solid var(--border); margin: 2.5rem 0; }

code {
  font-family: var(--font-mono);
  font-size: .9em;
  background: var(--ink-100);
  color: var(--blue-700);
  padding: .15em .45em;
  border-radius: var(--radius-sm);
}

/* 焦点可见性（可访问性） */
:focus-visible {
  outline: 2px solid var(--brand);
  outline-offset: 2px;
  border-radius: var(--radius-sm);
}

/* 跳过导航 */
.skip-link {
  position: absolute; left: -9999px; top: 0; z-index: 999;
  background: var(--brand); color: #fff; padding: .75rem 1.25rem;
  border-radius: 0 0 var(--radius) 0;
}
.skip-link:focus { left: 0; color: #fff; }

/* ---------- 布局 ---------- */
.container {
  width: 100%;
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 20px;
}
.container-narrow { max-width: var(--container-narrow); }

.section { padding: 64px 0; }
.section-sm { padding: 44px 0; }
.section-lg { padding: 84px 0; }
.section-soft { background: var(--bg-soft); }
.section-tint { background: linear-gradient(180deg, var(--blue-50) 0%, var(--white) 100%); }

.grid { display: grid; gap: 20px; }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }

/* ---------- 顶部导航 ---------- */
.site-header {
  position: sticky; top: 0; z-index: 100;
  background: rgba(255, 255, 255, .9);
  backdrop-filter: saturate(180%) blur(14px);
  -webkit-backdrop-filter: saturate(180%) blur(14px);
  border-bottom: 1px solid var(--border-soft);
}
.nav-wrap {
  display: flex; align-items: center; gap: 28px;
  min-height: 64px;
}
.brand {
  display: flex; align-items: center; gap: 9px;
  font-size: 1.15rem; font-weight: 800; letter-spacing: -.02em;
  color: var(--ink-900); flex-shrink: 0;
}
.brand:hover { color: var(--ink-900); }
.brand-mark {
  width: 30px; height: 30px; border-radius: 8px;
  background: linear-gradient(135deg, var(--blue-500), var(--blue-700));
  color: #fff; display: grid; place-items: center;
  font-size: .95rem; font-weight: 800; flex-shrink: 0;
}
.brand-sub { font-size: .7rem; font-weight: 500; color: var(--text-faint); letter-spacing: 0; }

.nav-menu {
  display: flex; align-items: center; gap: 4px;
  margin: 0; padding: 0; list-style: none;
  flex: 1;
}
.nav-menu li { margin: 0; }
.nav-menu a {
  display: block; padding: 8px 12px; border-radius: var(--radius-sm);
  font-size: .9375rem; font-weight: 500; color: var(--text-muted);
  white-space: nowrap;
}
.nav-menu a:hover { color: var(--brand); background: var(--blue-50); }
.nav-menu a[aria-current="page"] { color: var(--brand); font-weight: 600; }

.nav-actions { display: flex; align-items: center; gap: 10px; flex-shrink: 0; }

.nav-toggle {
  display: none; background: none; border: 1px solid var(--border);
  border-radius: var(--radius-sm); width: 38px; height: 34px;
  cursor: pointer; padding: 0; place-items: center;
}
.nav-toggle span { display: block; width: 16px; height: 2px; background: var(--ink-600); position: relative; }
.nav-toggle span::before, .nav-toggle span::after {
  content: ""; position: absolute; left: 0; width: 16px; height: 2px; background: var(--ink-600);
}
.nav-toggle span::before { top: -5px; }
.nav-toggle span::after { top: 5px; }

/* ---------- 按钮 ---------- */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: .5em;
  padding: 11px 22px; border-radius: var(--radius);
  font-size: .9375rem; font-weight: 600; line-height: 1.4;
  border: 1px solid transparent; cursor: pointer;
  transition: all .18s var(--ease); white-space: nowrap;
  font-family: inherit;
}
.btn-primary {
  background: var(--brand); color: #fff;
  box-shadow: var(--shadow-brand);
}
.btn-primary:hover { background: var(--brand-dark); color: #fff; transform: translateY(-1px); }
.btn-accent {
  background: var(--accent); color: #fff;
  box-shadow: 0 8px 24px rgba(255, 125, 0, .25);
}
.btn-accent:hover { background: var(--orange-600); color: #fff; transform: translateY(-1px); }
.btn-ghost {
  background: var(--white); color: var(--text); border-color: var(--border);
}
.btn-ghost:hover { border-color: var(--blue-300); color: var(--brand); background: var(--blue-50); }
.btn-link { padding: 0; color: var(--brand); font-weight: 600; background: none; box-shadow: none; }
.btn-link:hover { color: var(--brand-dark); }
.btn-lg { padding: 14px 30px; font-size: 1rem; }
.btn-sm { padding: 8px 16px; font-size: .875rem; }
.btn-block { width: 100%; }

.btn-row { display: flex; flex-wrap: wrap; gap: 12px; }
.btn-row-center { justify-content: center; }

/* ---------- 面包屑 ---------- */
.breadcrumb {
  display: flex; flex-wrap: wrap; align-items: center; gap: 6px;
  margin: 0 0 18px; padding: 0; list-style: none;
  font-size: .8125rem; color: var(--text-faint);
}
.breadcrumb li { margin: 0; display: flex; align-items: center; gap: 6px; }
.breadcrumb li::after { content: "/"; color: var(--ink-300); }
.breadcrumb li:last-child::after { display: none; }
.breadcrumb a { color: var(--text-faint); }
.breadcrumb a:hover { color: var(--brand); }
.breadcrumb [aria-current="page"] { color: var(--text-muted); }

/* ---------- Hero ---------- */
.hero {
  padding: 68px 0 60px;
  background:
    radial-gradient(900px 420px at 85% -10%, rgba(22, 93, 255, .10), transparent 62%),
    radial-gradient(700px 380px at 5% 0%, rgba(255, 125, 0, .07), transparent 58%),
    linear-gradient(180deg, var(--blue-50) 0%, #fff 78%);
  border-bottom: 1px solid var(--border-soft);
}
.hero-grid {
  display: grid; grid-template-columns: 1.15fr .85fr;
  gap: 52px; align-items: center;
}
.hero h1 { margin-bottom: .35em; }
.hero-lead {
  font-size: 1.0625rem; color: var(--text-muted);
  max-width: 40em; margin-bottom: 1.5em;
}
.hero-note {
  margin-top: 1.5em; font-size: .8125rem; color: var(--text-faint);
}

/* 事实速览卡（GEO 友好：AI 易抽取） */
.facts-card {
  background: var(--white); border: 1px solid var(--border);
  border-radius: var(--radius-lg); padding: 24px;
  box-shadow: var(--shadow);
}
.facts-card h2, .facts-card h3 {
  font-size: .78rem; text-transform: uppercase; letter-spacing: .09em;
  color: var(--text-faint); font-weight: 700; margin-bottom: 14px;
}
.facts-list { margin: 0; padding: 0; list-style: none; }
.facts-list li {
  display: flex; justify-content: space-between; gap: 16px;
  padding: 9px 0; border-bottom: 1px dashed var(--border);
  font-size: .875rem; margin: 0;
}
.facts-list li:last-child { border-bottom: 0; }
.facts-list dt, .facts-list .k { color: var(--text-faint); flex-shrink: 0; }
.facts-list .v { color: var(--text-strong); font-weight: 600; text-align: right; }

/* ---------- 徽章 / 标签 ---------- */
.badge {
  display: inline-flex; align-items: center; gap: .4em;
  padding: 4px 11px; border-radius: 999px;
  font-size: .75rem; font-weight: 600; line-height: 1.6;
  background: var(--blue-50); color: var(--blue-600);
  border: 1px solid var(--blue-100);
}
.badge-accent { background: var(--orange-50); color: var(--orange-600); border-color: var(--orange-100); }
.badge-neutral { background: var(--ink-100); color: var(--text-muted); border-color: var(--border); }
.badge-row { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 18px; }

/* ---------- 卡片 ---------- */
.card {
  background: var(--white); border: 1px solid var(--border);
  border-radius: var(--radius-lg); padding: 24px;
  transition: all .2s var(--ease);
}
.card-hover:hover {
  border-color: var(--blue-200);
  box-shadow: var(--shadow);
  transform: translateY(-3px);
}
.card h3 { margin-bottom: .4em; font-size: 1.0625rem; }
.card p { font-size: .9375rem; color: var(--text-muted); margin-bottom: 0; }
.card-icon {
  width: 42px; height: 42px; border-radius: var(--radius);
  background: var(--blue-50); color: var(--brand);
  display: grid; place-items: center; margin-bottom: 16px;
  font-size: 1.2rem;
}
.card-num {
  display: inline-grid; place-items: center;
  width: 26px; height: 26px; border-radius: 50%;
  background: var(--brand); color: #fff;
  font-size: .8125rem; font-weight: 700; margin-bottom: 12px;
}

/* ---------- 表格 ---------- */
.table-wrap {
  overflow-x: auto; -webkit-overflow-scrolling: touch;
  border: 1px solid var(--border); border-radius: var(--radius-lg);
  background: var(--white); margin-bottom: 22px;
}
table {
  width: 100%; border-collapse: collapse;
  font-size: .9rem; min-width: 560px;
}
caption {
  caption-side: top; text-align: left; padding: 16px 20px 8px;
  font-size: .8125rem; color: var(--text-faint); font-weight: 600;
}
th, td {
  padding: 13px 18px; text-align: left;
  border-bottom: 1px solid var(--border-soft);
  vertical-align: top;
}
thead th {
  background: var(--ink-50); font-weight: 700; color: var(--text-strong);
  font-size: .8125rem; white-space: nowrap;
  border-bottom: 1px solid var(--border);
}
tbody tr:last-child td { border-bottom: 0; }
tbody tr:hover { background: var(--blue-50); }
td .yes { color: var(--green-500); font-weight: 700; }
td .no { color: var(--ink-400); }
.col-highlight { background: rgba(22, 93, 255, .05); }

/* ---------- 列表样式 ---------- */
.check-list, .plain-list { list-style: none; padding: 0; margin: 0; }
.check-list li {
  position: relative; padding-left: 28px; margin-bottom: .7em;
  font-size: .9375rem; color: var(--text);
}
.check-list li::before {
  content: ""; position: absolute; left: 0; top: .48em;
  width: 16px; height: 9px;
  border-left: 2.5px solid var(--brand); border-bottom: 2.5px solid var(--brand);
  transform: rotate(-45deg); border-radius: 1px;
}
.plain-list li { font-size: .9375rem; margin-bottom: .6em; color: var(--text-muted); }

/* ---------- FAQ（GEO 核心） ---------- */
.faq-list { margin: 0; padding: 0; list-style: none; border-top: 1px solid var(--border); }
.faq-item { border-bottom: 1px solid var(--border); margin: 0; }
.faq-item summary {
  display: flex; align-items: flex-start; justify-content: space-between; gap: 18px;
  padding: 20px 4px; cursor: pointer; list-style: none;
  font-size: 1rem; font-weight: 600; color: var(--text-strong);
  transition: color .18s var(--ease);
}
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary::after {
  content: "+"; flex-shrink: 0; font-size: 1.35rem; line-height: 1;
  font-weight: 400; color: var(--brand); transition: transform .2s var(--ease);
}
.faq-item[open] summary::after { transform: rotate(45deg); }
.faq-item summary:hover { color: var(--brand); }
.faq-body { padding: 0 4px 22px; font-size: .9375rem; color: var(--text-muted); }
.faq-body p { margin-bottom: .7em; }

/* ---------- 提示框 ---------- */
.callout {
  display: flex; gap: 14px; padding: 18px 20px;
  border-radius: var(--radius); border-left: 4px solid var(--brand);
  background: var(--blue-50); margin: 24px 0; font-size: .9375rem;
}
.callout-accent { border-left-color: var(--accent); background: var(--orange-50); }
.callout-neutral { border-left-color: var(--ink-300); background: var(--ink-50); }
.callout p { margin: 0; color: var(--text); }
.callout-title { font-weight: 700; color: var(--text-strong); display: block; margin-bottom: .2em; }

/* 快速答案块（AI 摘要首选引用位置） */
.answer-box {
  background: linear-gradient(180deg, var(--blue-50), #fff);
  border: 1px solid var(--blue-100);
  border-radius: var(--radius-lg);
  padding: 22px 24px; margin-bottom: 30px;
}
.answer-box .label {
  display: block; font-size: .75rem; font-weight: 700;
  text-transform: uppercase; letter-spacing: .08em;
  color: var(--blue-600); margin-bottom: .6em;
}
.answer-box p { font-size: 1rem; color: var(--text); margin: 0; }

/* ---------- 步骤流程 ---------- */
.steps { counter-reset: step; margin: 0; padding: 0; list-style: none; }
.steps > li {
  position: relative; padding-left: 56px; padding-bottom: 28px;
  border-left: 2px solid var(--border); margin-left: 17px;
}
.steps > li:last-child { border-left-color: transparent; padding-bottom: 0; }
.steps > li::before {
  counter-increment: step; content: counter(step);
  position: absolute; left: -18px; top: -2px;
  width: 34px; height: 34px; border-radius: 50%;
  background: var(--brand); color: #fff;
  display: grid; place-items: center;
  font-size: .875rem; font-weight: 700;
  box-shadow: 0 0 0 4px var(--white);
}
.steps h3 { font-size: 1.0625rem; margin-bottom: .3em; }
.steps p, .steps ul { font-size: .9375rem; color: var(--text-muted); }

/* ---------- 数据统计 ---------- */
.stat-row {
  display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px;
  text-align: center;
}
.stat-num {
  display: block; font-size: clamp(1.6rem, 3.5vw, 2.25rem);
  font-weight: 800; color: var(--brand); line-height: 1.1;
  letter-spacing: -.02em;
}
.stat-label { font-size: .875rem; color: var(--text-muted); margin-top: 6px; display: block; }

/* ---------- 评价卡 ---------- */
.quote {
  background: var(--white); border: 1px solid var(--border);
  border-radius: var(--radius-lg); padding: 22px; margin: 0;
}
.quote p { font-size: .9375rem; color: var(--text); margin-bottom: 14px; }
.quote footer { font-size: .8125rem; color: var(--text-faint); }
.quote footer strong { display: block; color: var(--text-strong); font-size: .875rem; }

/* ---------- CTA 区块 ---------- */
.cta-band {
  background: linear-gradient(120deg, var(--blue-700), var(--blue-500) 55%, #3d7bff);
  color: #fff; padding: 60px 0; text-align: center;
  border-radius: var(--radius-xl);
  margin: 0 auto;
  position: relative; overflow: hidden;
}
.cta-band::after {
  content: ""; position: absolute; inset: 0;
  background: radial-gradient(600px 300px at 80% 120%, rgba(255,255,255,.16), transparent 60%);
  pointer-events: none;
}
.cta-band h2 { color: #fff; }
.cta-band p { color: rgba(255, 255, 255, .86); max-width: 44em; margin: 0 auto 1.6em; font-size: 1.0625rem; }
.cta-band .btn-ghost { background: rgba(255,255,255,.14); border-color: rgba(255,255,255,.4); color: #fff; }
.cta-band .btn-ghost:hover { background: rgba(255,255,255,.24); color: #fff; }

/* ---------- 文章正文排版 ---------- */
.prose { font-size: 1rem; }
.prose h2 { margin-top: 2.2em; padding-top: .2em; }
.prose h2:first-child { margin-top: 0; }
.prose h3 { margin-top: 1.7em; }
.prose ul, .prose ol { margin-bottom: 1.2em; }
.prose blockquote {
  margin: 1.5em 0; padding: 4px 0 4px 20px;
  border-left: 4px solid var(--blue-200);
  color: var(--text-muted); font-style: normal;
}
.prose .table-wrap { margin: 1.6em 0; }

/* 目录 */
.toc {
  background: var(--bg-soft); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 18px 22px; margin-bottom: 32px;
}
.toc strong { display: block; font-size: .875rem; margin-bottom: .6em; }
.toc ol { margin: 0; padding-left: 1.25em; font-size: .9rem; }
.toc li { margin-bottom: .3em; }
.toc a { color: var(--text-muted); }
.toc a:hover { color: var(--brand); }

/* ---------- 页脚 ---------- */
.site-footer {
  background: var(--ink-50);
  border-top: 1px solid var(--border);
  padding: 52px 0 28px;
  margin-top: 72px;
  font-size: .875rem;
}
.footer-grid {
  display: grid; grid-template-columns: 1.6fr 1fr 1fr 1fr;
  gap: 36px; margin-bottom: 36px;
}
.footer-brand p { color: var(--text-muted); font-size: .875rem; max-width: 30em; }
.footer-col h3 {
  font-size: .8125rem; font-weight: 700; text-transform: uppercase;
  letter-spacing: .07em; color: var(--text-faint); margin-bottom: 14px;
}
.footer-col ul { list-style: none; margin: 0; padding: 0; }
.footer-col li { margin-bottom: 9px; }
.footer-col a { color: var(--text-muted); }
.footer-col a:hover { color: var(--brand); }
.footer-bottom {
  border-top: 1px solid var(--border); padding-top: 22px;
  display: flex; flex-wrap: wrap; justify-content: space-between; gap: 12px;
  color: var(--text-faint); font-size: .8125rem;
}
.footer-bottom p { margin: 0; }
.footer-icp {
  margin: 14px 0 0; font-size: .8125rem; color: var(--text-faint);
}
.footer-icp a { color: var(--text-faint); }
.footer-icp a:hover { color: var(--brand); }
.footer-disclaimer {
  margin-top: 18px; padding-top: 18px; border-top: 1px dashed var(--border);
  font-size: .75rem; color: var(--text-faint); line-height: 1.7;
}

/* ---------- 页头（内页） ---------- */
.page-head {
  padding: 40px 0 36px;
  background: linear-gradient(180deg, var(--blue-50), var(--white));
  border-bottom: 1px solid var(--border-soft);
}
.page-head h1 { margin-bottom: .3em; }
.page-head .lead { font-size: 1.0625rem; color: var(--text-muted); max-width: 46em; margin: 0; }
.page-head-meta {
  margin-top: 16px; font-size: .8125rem; color: var(--text-faint);
  display: flex; flex-wrap: wrap; gap: 16px;
}

/* ---------- 内链导航块 ---------- */
.link-cards { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; }
.link-card {
  display: block; background: var(--white); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 18px 20px;
  transition: all .2s var(--ease);
}
.link-card:hover { border-color: var(--blue-300); box-shadow: var(--shadow-sm); transform: translateY(-2px); }
.link-card strong { display: block; color: var(--text-strong); margin-bottom: .25em; font-size: .9375rem; }
.link-card span { font-size: .8125rem; color: var(--text-faint); }

/* ---------- 工具类 ---------- */
.text-center { text-align: center; }
.text-muted { color: var(--text-muted); }
.text-faint { color: var(--text-faint); }
.small { font-size: .875rem; }
.mt-0 { margin-top: 0; }
.mt-1 { margin-top: 12px; }
.mt-2 { margin-top: 24px; }
.mt-3 { margin-top: 36px; }
.mb-0 { margin-bottom: 0; }
.mb-1 { margin-bottom: 12px; }
.mb-2 { margin-bottom: 24px; }
.mb-3 { margin-bottom: 36px; }
.mx-auto { margin-left: auto; margin-right: auto; }
.sr-only {
  position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px;
  overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; border: 0;
}
.section-head { max-width: 46em; margin-bottom: 36px; }
.section-head.center { margin-left: auto; margin-right: auto; text-align: center; }
.section-head p { color: var(--text-muted); font-size: 1rem; margin-bottom: 0; }

/* ---------- 内容区块 ---------- */
.block { margin-top: 52px; }
.block:first-child { margin-top: 0; }
.block-head { max-width: 48em; margin-bottom: 26px; }
.block-head h2 { margin-bottom: .35em; }
.block-head p { color: var(--text-muted); margin: 0; font-size: 1rem; }

/* 卡片精简模式 */
.grid-4 .card { padding: 18px 20px; }
.grid-4 .card h3 { font-size: .9375rem; }
.grid-4 .card p { font-size: .8125rem; }

/* 索引页跳转条 */
.toc-inline { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 30px; }

/* ---------- 响应式 ---------- */
@media (max-width: 1000px) {
  .hero-grid { grid-template-columns: 1fr; gap: 36px; }
  .footer-grid { grid-template-columns: 1fr 1fr; gap: 28px; }
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
  .stat-row { grid-template-columns: repeat(2, 1fr); gap: 28px; }
  .link-cards { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 860px) {
  .nav-toggle { display: grid; }
  .nav-menu {
    display: none; position: absolute; left: 0; right: 0; top: 100%;
    flex-direction: column; align-items: stretch; gap: 0;
    background: var(--white); border-bottom: 1px solid var(--border);
    padding: 8px 20px 18px; box-shadow: var(--shadow);
  }
  .nav-menu.is-open { display: flex; }
  .nav-menu a { padding: 12px 4px; border-bottom: 1px solid var(--border-soft); border-radius: 0; }
  .nav-actions .btn-ghost { display: none; }
  .nav-wrap { position: relative; }
  .grid-3 { grid-template-columns: 1fr; }
}

@media (max-width: 620px) {
  body { font-size: 15.5px; }
  .section, .section-lg { padding: 44px 0; }
  .hero { padding: 44px 0 40px; }
  .grid-2, .grid-4, .link-cards { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr; }
  .container { padding: 0 16px; }
  .card, .facts-card { padding: 20px; }
  .cta-band { border-radius: var(--radius-lg); padding: 44px 0; }
  .btn-row .btn { flex: 1 1 auto; }
  .stat-row { grid-template-columns: repeat(2, 1fr); gap: 24px; }
  table { font-size: .85rem; }
  th, td { padding: 11px 14px; }
}

/* 打印 */
@media print {
  .site-header, .site-footer, .cta-band, .btn { display: none; }
  body { font-size: 11pt; }
  a { color: #000; }
}