/* ==========================================================================
   HeavyLoad 中文网 · 唯一样式表
   依据：design-spec.md v1.0（色彩/字体/间距变量、组件 9 类、图标规范）
   约束：无框架、无外部请求、移动优先（min-width 断点 769 / 1200）
   ========================================================================== */

/* ---------- 1. 设计变量（:root，组件只引用变量） ---------- */
:root {
  /* 品牌蓝色阶 */
  --brand-50: #EAF2FA;
  --brand-100: #D3E4F5;
  --brand-200: #A8CBE8;
  --brand-300: #80B0E0;
  --brand-400: #5C9BD2;
  --brand-500: #3080C0;
  --brand-600: #2870AC;  /* 交互主色：主按钮/链接/当前导航 */
  --brand-700: #1F5A90;  /* 正文级链接、悬停加深 */
  --brand-800: #17446E;
  --brand-900: #0F2D4A;

  /* 中性灰阶（slate） */
  --gray-50: #F8FAFC;
  --gray-100: #F1F5F9;
  --gray-200: #E2E8F0;
  --gray-300: #CBD5E1;
  --gray-400: #94A3B8;
  --gray-500: #64748B;
  --gray-600: #475569;
  --gray-800: #1E293B;
  --gray-900: #0F172A;

  /* 语义色 */
  --success: #166534;
  --success-bg: #F0FDF4;
  --success-border: #BBF7D0;
  --warning: #92400E;
  --warning-bg: #FEFCE8;
  --warning-border: #FDE68A;
  --danger: #B91C1C;
  --danger-bg: #FEF2F2;
  --danger-border: #FECACA;
  --info: #2870AC;
  --info-bg: #EAF2FA;
  --info-border: #A8CBE8;

  /* 页脚深底 */
  --footer-bg: #0F1D2E;

  /* 字体栈（系统字体，零外部请求） */
  --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, "Cascadia Mono", Consolas,
    "PingFang SC", "Microsoft YaHei", monospace;

  /* 布局 */
  --container-max: 1200px;
  --header-h: 64px;
  --section-py: 48px;

  /* 圆角与描边 */
  --radius-s: 6px;
  --radius-m: 10px;
  --radius-l: 14px;
  --radius-pill: 999px;
  --border: 1px solid var(--gray-200);
  --shadow-float: 0 4px 16px rgba(15, 29, 46, .12); /* 唯一允许阴影：浮层 */
}

@media (min-width: 769px) {
  :root { --section-py: 64px; }
}
@media (min-width: 1200px) {
  :root { --section-py: 80px; }
}

/* ---------- 2. 基础与重置 ---------- */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: 88px; /* 64px 吸顶导航 + 呼吸 */
  -webkit-text-size-adjust: 100%;
}
.page-features { scroll-padding-top: 148px; } /* features 吸顶锚点导航额外占位 */

body {
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.75;
  color: var(--gray-800);
  background: var(--gray-50);
}

img { max-width: 100%; height: auto; }

h1, h2, h3, h4 {
  color: var(--gray-900);
  line-height: 1.35;
  font-weight: 600;
}

ul, ol { list-style-position: inside; }

a {
  color: var(--brand-700);
  text-decoration: underline;
  text-underline-offset: 3px;
}
a:hover { color: var(--brand-800); }

code, .mono {
  font-family: var(--font-mono);
  font-size: .92em;
}

/* 焦点态：全局可见 */
:focus-visible {
  outline: 2px solid var(--brand-700);
  outline-offset: 2px;
}
.site-footer :focus-visible,
.modal-overlay :focus-visible {
  outline-color: var(--brand-300);
}

/* skip-link：默认视觉隐藏，聚焦时出现 */
.skip-link {
  position: absolute;
  left: 12px;
  top: -56px;
  z-index: 300;
  padding: 10px 18px;
  background: #fff;
  border: 2px solid var(--brand-700);
  border-radius: var(--radius-m);
  color: var(--brand-700);
  font-weight: 600;
  text-decoration: none;
  transition: top .15s ease-out;
}
.skip-link:focus { top: 12px; }

/* 视觉隐藏（屏幕阅读器可用） */
.visually-hidden {
  position: absolute !important;
  width: 1px; height: 1px;
  margin: -1px; padding: 0;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap; border: 0;
}

/* ---------- 3. 布局容器 ---------- */
.container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 16px;
}
@media (min-width: 769px) {
  .container { padding: 0 24px; }
}

.section { padding: var(--section-py) 0; }
.section-white { background: #fff; border-top: 1px solid var(--gray-200); border-bottom: 1px solid var(--gray-200); }

.section-head { max-width: 760px; margin-bottom: 36px; }
.section-title { font-size: 24px; margin-bottom: 12px; }
.section-desc { color: var(--gray-600); font-size: 16px; }
/* 章节标题：显式字号，桌面端与 1200 容器匹配 */
.section-head h2 { font-size: 24px; letter-spacing: -.01em; }
@media (min-width: 769px) {
  .section-title { font-size: 26px; }
  .section-head h2 { font-size: 27px; }
}
@media (min-width: 1200px) {
  .section-title { font-size: 28px; }
  .section-head h2 { font-size: 30px; }
}

/* 正文栏（guide/features 长文） */
.prose { max-width: 760px; }
.prose h3 { font-size: 18px; margin: 32px 0 12px; }
.prose p { margin-bottom: 14px; }
.prose ul, .prose ol { margin: 0 0 14px; padding-left: 4px; }
.prose li { margin-bottom: 8px; }
@media (min-width: 769px) {
  .prose h3 { font-size: 20px; }
}

/* 网格 */
.grid { display: grid; gap: 24px; }
.grid-2 { grid-template-columns: 1fr; }
.grid-3 { grid-template-columns: 1fr; }
@media (min-width: 769px) {
  .grid-2 { grid-template-columns: repeat(2, 1fr); }
  .grid-3 { grid-template-columns: repeat(2, 1fr); }
}
@media (min-width: 900px) {
  .grid-3 { grid-template-columns: repeat(3, 1fr); }
}

/* ---------- 4. 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  height: 40px;
  padding: 0 20px;
  border: none;
  border-radius: var(--btn-radius, var(--radius-m));
  font-family: var(--font-sans);
  font-size: 16px;
  font-weight: 600;
  line-height: 1;
  text-decoration: none;
  cursor: pointer;
  white-space: nowrap;
  transition: background-color .15s, border-color .15s, color .15s;
}
.btn-lg { height: 48px; padding: 0 24px; font-size: 17px; }
.btn-sm { height: 32px; padding: 0 16px; font-size: 14px; }
.btn-nav { height: 36px; padding: 0 16px; font-size: 14px; }

.btn-primary { background: var(--brand-600); color: #fff; }
.btn-primary:hover, .btn-primary:focus-visible { background: var(--brand-700); color: #fff; }
.btn-primary:focus-visible { outline-color: var(--brand-300); }

.btn-secondary {
  background: #fff;
  color: var(--brand-700);
  border: 1.5px solid var(--brand-600);
}
.btn-secondary:hover, .btn-secondary:focus-visible {
  background: var(--brand-50);
  color: var(--brand-700);
}

.btn-text {
  background: none;
  border: none;
  height: auto;
  padding: 0;
  color: var(--brand-700);
  text-decoration: underline;
  text-underline-offset: 3px;
  font-weight: 600;
}
.btn-text:hover { color: var(--brand-800); }

/* ---------- 5. 徽章 ---------- */
.badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  border-radius: var(--radius-pill);
  font-size: 14px;
  font-weight: 600;
  padding: 4px 12px;
  line-height: 1.4;
}
.badge-free { background: var(--success-bg); color: var(--success); border: 1px solid var(--success-border); }
.badge-ver { background: var(--brand-50); color: var(--brand-600); border: 1px solid var(--brand-200); font-family: var(--font-mono); font-size: 13px; }
.badge-new { background: var(--brand-50); color: var(--brand-600); border: 1px solid var(--brand-200); font-size: 13px; }
.badge-rec {
  border-radius: var(--radius-s);
  background: var(--brand-600);
  color: #fff;
  font-size: 12px;
  font-weight: 600;
  padding: 2px 8px;
}

/* ---------- 6. 吸顶导航栏 ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: #fff;
  border-bottom: 1px solid var(--gray-200);
}

.site-header .nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  height: var(--header-h);
}

.brand {
  display: inline-flex;
  align-items: center;
  flex-shrink: 0;
  text-decoration: none;
}
.brand img { display: block; width: 168px; height: 45px; }

.main-nav { display: none; }
.main-nav ul { display: flex; gap: 4px; list-style: none; margin: 0; padding: 0; }
.main-nav a {
  display: flex;
  align-items: center;
  height: var(--header-h);
  padding: 0 14px;
  color: var(--gray-800);
  font-size: 15px;
  font-weight: 500;
  text-decoration: none;
  position: relative;
  transition: color .15s;
}
.main-nav a:hover { color: var(--brand-700); }
.main-nav a[aria-current="page"] {
  color: var(--brand-700);
  font-weight: 600;
}
.main-nav a[aria-current="page"]::after {
  content: "";
  position: absolute;
  left: 14px;
  right: 14px;
  bottom: 0;
  height: 2px;
  background: var(--brand-600);
}
.header-cta { display: none; }

/* 汉堡按钮（仅 ≤768 显示） */
.menu-toggle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  background: none;
  border: none;
  border-radius: var(--radius-s);
  color: var(--gray-800);
  cursor: pointer;
}
.menu-toggle:hover { color: var(--brand-700); background: var(--brand-50); }

/* 移动端抽屉 */
.mobile-nav {
  display: none;
  background: #fff;
  border-top: 1px solid var(--gray-200);
  border-bottom: 1px solid var(--gray-200);
  box-shadow: var(--shadow-float);
}
.mobile-nav.open { display: block; }
.mobile-nav ul { list-style: none; margin: 0; padding: 8px 16px 16px; }
.mobile-nav li + li { border-top: 1px solid var(--gray-100); }
.mobile-nav a:not(.btn) {
  display: flex;
  align-items: center;
  min-height: 48px;
  padding: 0 8px;
  color: var(--gray-800);
  font-size: 16px;
  font-weight: 500;
  text-decoration: none;
}
.mobile-nav a:not(.btn):hover { color: var(--brand-700); }
.mobile-nav a[aria-current="page"] { color: var(--brand-700); font-weight: 600; }
.mobile-nav .btn { width: 100%; margin-top: 12px; }

body.nav-open::after {
  content: "";
  position: fixed;
  inset: 0;
  background: rgba(15, 29, 46, .4);
  z-index: 99;
}

@media (min-width: 769px) {
  .main-nav { display: block; }
  .header-cta { display: inline-flex; }
  .menu-toggle { display: none; }
  .mobile-nav { display: none !important; }
  body.nav-open::after { content: none; }
}

/* ---------- 7. Hero（首页首屏） ---------- */
.hero {
  background: #fff;
  border-bottom: 1px solid var(--gray-200);
  padding: 48px 0;
}
.hero-grid {
  display: grid;
  gap: 40px;
  align-items: center;
}
.hero-badges { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 20px; }
.hero h1 {
  font-size: 30px;
  font-weight: 700;
  line-height: 1.25;
  margin-bottom: 16px;
}
.hero-sub {
  font-size: 16px;
  color: var(--gray-600);
  line-height: 1.75;
  max-width: 34em;
  margin-bottom: 28px;
}
.hero-actions { display: flex; gap: 12px; flex-wrap: wrap; margin-bottom: 20px; }
.hero-trust {
  display: flex;
  gap: 8px 20px;
  flex-wrap: wrap;
  color: var(--gray-500);
  font-size: 14px;
}
.hero-trust li { display: flex; align-items: center; gap: 6px; list-style: none; }
.hero-trust svg { color: var(--brand-600); flex-shrink: 0; }

/* Hero 右侧：真实软件界面截图（拟真窗口 + 悬浮投影） */
.hero-figure {
  margin: 0;
  border: 1px solid var(--gray-200);
  border-radius: var(--radius-l);
  background: #fff;
  overflow: hidden;
  box-shadow: 0 26px 50px -30px rgba(15, 23, 42, .34), 0 4px 14px -8px rgba(15, 23, 42, .10);
}
.hero-figure img {
  display: block;
  width: 100%;
  height: auto;
  border-bottom: 1px solid var(--gray-100);
}
.hero-figure figcaption {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 11px 16px;
  font-size: 12.5px;
  line-height: 1.5;
  color: var(--gray-500);
  background: #fff;
}
.hero-shot-dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--brand-600);
  box-shadow: 0 0 0 3px var(--brand-50);
  flex-shrink: 0;
}

@media (min-width: 769px) {
  .hero { padding: 64px 0; }
  .hero-grid { grid-template-columns: 5fr 6fr; gap: 48px; }
  .hero h1 { font-size: 38px; }
  .hero-sub { font-size: 17px; }
}
@media (min-width: 1200px) {
  .hero { padding: 80px 0; }
  .hero h1 { font-size: 44px; }
}

/* ---------- 8. 页头（内页 Page Header） ---------- */
.page-head {
  background: #fff;
  border-bottom: 1px solid var(--gray-200);
  padding: 40px 0 44px;
}
.page-head .badge { margin-bottom: 14px; }
.page-head h1 { font-size: 28px; line-height: 1.3; margin-bottom: 12px; }
.page-head-desc { color: var(--gray-600); max-width: 760px; }
@media (min-width: 769px) {
  .page-head { padding: 48px 0 52px; }
  .page-head h1 { font-size: 32px; }
  .page-head-desc { font-size: 17px; }
}
@media (min-width: 1200px) {
  .page-head h1 { font-size: 36px; }
}

/* ---------- 9. 卡片 ---------- */
.card {
  display: flex;
  flex-direction: column;
  background: #fff;
  border: var(--border);
  border-radius: var(--radius-l);
  padding: 24px;
  transition: border-color .18s, transform .18s;
}
.card:hover { border-color: var(--brand-200); transform: translateY(-2px); }
.card-icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 48px;
  height: 48px;
  border-radius: var(--radius-m);
  background: var(--brand-50);
  color: var(--brand-600);
  margin-bottom: 16px;
  transition: background-color .15s;
}
.card:hover .card-icon { background: var(--brand-100); }
.card-title { font-size: 18px; margin-bottom: 8px; }
.card-desc { color: var(--gray-600); font-size: 15px; flex: 1; }
.card-link { margin-top: 16px; font-weight: 600; font-size: 15px; }

/* 带图标勾选的优势列表 */
.check-list { list-style: none; padding: 0; }
.check-list li {
  display: flex;
  gap: 12px;
  align-items: flex-start;
  padding: 12px 0;
  border-bottom: 1px solid var(--gray-100);
}
.check-list li:last-child { border-bottom: none; }
.check-list svg { color: var(--brand-600); flex-shrink: 0; margin-top: 4px; }
.check-list strong { color: var(--gray-900); font-weight: 600; }

@media (min-width: 769px) {
  .card-title { font-size: 20px; }
}

/* ---------- 10. 表格 ---------- */
.table-wrap {
  border: 1px solid var(--gray-300);
  border-radius: var(--radius-m);
  overflow-x: auto;
  background: #fff;
}
.table-wrap table {
  width: 100%;
  min-width: 560px;
  border-collapse: collapse;
}
.table-wrap th {
  background: var(--gray-100);
  color: var(--gray-800);
  font-size: 14px;
  font-weight: 600;
  text-align: left;
  padding: 12px 16px;
  border-bottom: 1px solid var(--gray-200);
  white-space: nowrap;
}
.table-wrap td {
  padding: 12px 16px;
  font-size: 15px;
  color: var(--gray-800);
  border-bottom: 1px solid var(--gray-200);
  vertical-align: top;
}
.table-wrap tr:last-child td { border-bottom: none; }
.table-wrap td:first-child { font-weight: 500; }
.cell-ok { color: var(--success); display: inline-flex; align-items: center; gap: 6px; white-space: nowrap; }
.cell-no { color: var(--danger); display: inline-flex; align-items: center; gap: 6px; white-space: nowrap; }

/* ---------- 11. 步骤指示器 ---------- */
.steps {
  display: grid;
  gap: 32px;
  position: relative;
}
.step { display: flex; flex-direction: column; align-items: center; text-align: center; gap: 12px; position: relative; z-index: 1; }
.step-num {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: var(--brand-600);
  color: #fff;
  font-size: 18px;
  font-weight: 700;
  flex-shrink: 0;
}
.step h3 { font-size: 18px; }
.step p { color: var(--gray-600); font-size: 15px; }

@media (min-width: 769px) {
  .steps { grid-template-columns: repeat(3, 1fr); }
  .steps::before {
    content: "";
    position: absolute;
    top: 20px;
    left: 16.66%;
    right: 16.66%;
    height: 2px;
    background: var(--gray-200);
    z-index: 0;
  }
  .step { text-align: center; }
}
@media (max-width: 768px) {
  .step { flex-direction: row; text-align: left; align-items: flex-start; }
  .step-num { margin-top: 2px; }
}

/* ---------- 12. 提示条 callout ---------- */
.callout {
  display: flex;
  gap: 12px;
  align-items: flex-start;
  padding: 14px 16px;
  border-left: 4px solid;
  border-radius: 0 var(--radius-s) var(--radius-s) 0;
  font-size: 15px;
  line-height: 1.7;
  margin: 16px 0;
}
.callout svg { flex-shrink: 0; margin-top: 3px; }
.callout p { margin: 0; }
.callout strong { font-weight: 600; }
.callout-info { border-left-color: var(--info); background: var(--info-bg); color: var(--info); }
.callout-warning { border-left-color: var(--warning); background: var(--warning-bg); color: var(--warning); }
.callout-danger { border-left-color: var(--danger); background: var(--danger-bg); color: var(--danger); }
.callout-success { border-left-color: var(--success); background: var(--success-bg); color: var(--success); }

/* ---------- 13. FAQ 折叠 ---------- */
.faq-list { display: grid; gap: 12px; max-width: 860px; }
.faq-item {
  background: #fff;
  border: 1px solid var(--gray-200);
  border-radius: var(--radius-m);
}
.faq-item summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 16px 20px;
  cursor: pointer;
  font-size: 16px;
  font-weight: 600;
  color: var(--gray-900);
  list-style: none;
  border-radius: var(--radius-m);
  transition: color .15s;
}
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary:hover { color: var(--brand-700); }
.faq-item summary svg {
  flex-shrink: 0;
  color: var(--brand-600);
  transition: transform .2s;
}
.faq-item[open] summary svg { transform: rotate(180deg); }
.faq-answer {
  padding: 0 20px 18px;
  color: var(--gray-600);
  font-size: 16px;
  line-height: 1.75;
}
.faq-answer p + p { margin-top: 10px; }
.faq-answer ul, .faq-answer ol { margin: 10px 0; padding-left: 20px; }
.faq-answer li { margin-bottom: 6px; }

/* ---------- 14. 下载弹窗 Modal（F1） ---------- */
.modal-overlay {
  position: fixed;
  inset: 0;
  z-index: 200;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 16px;
  background: rgba(15, 29, 46, .5);
  opacity: 0;
  transition: opacity .2s ease-out;
}
.modal-overlay[hidden] { display: none; }
.modal-overlay.open { opacity: 1; }

.modal {
  width: min(480px, 100%);
  background: #fff;
  border-radius: var(--radius-l);
  padding: 32px 32px 28px;
  box-shadow: var(--shadow-float);
  transform: translateY(8px);
  transition: transform .2s ease-out;
}
.modal-overlay.open .modal { transform: translateY(0); }

.modal-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 8px;
}
.modal-header h2 { font-size: 20px; font-weight: 600; }
.modal-close {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  margin: -8px -8px -8px 0;
  background: none;
  border: none;
  border-radius: var(--radius-s);
  color: var(--gray-600);
  cursor: pointer;
}
.modal-close:hover { color: var(--gray-900); background: var(--gray-100); }

.modal-sub { color: var(--gray-600); font-size: 14px; margin-bottom: 24px; }

.qr-grid { display: grid; gap: 16px; }
.qr-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  background: #fff;
  border: 1px solid var(--gray-200);
  border-radius: var(--radius-l);
  padding: 16px;
}
.qr-img {
  display: block;
  width: 160px;
  height: auto;
  border-radius: 6px;
  background: #fff;
}
.qr-name { font-size: 16px; font-weight: 600; color: var(--gray-800); margin: 4px 0 0; }
.qr-hint { font-size: 14px; color: var(--gray-600); margin: 0; }

@media (min-width: 480px) {
  .qr-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 479px) {
  .modal { padding: 24px 20px 20px; }
}

/* ---------- 15. 页脚 ---------- */
.site-footer {
  background: var(--footer-bg);
  color: #fff;
  padding-top: 48px;
  margin-top: var(--section-py);
}
.footer-grid {
  display: grid;
  gap: 32px;
  padding-bottom: 40px;
}
.footer-brand img { width: 168px; height: 45px; margin-bottom: 14px; }
.footer-brand p { color: var(--gray-400); font-size: 14px; line-height: 1.7; }
.footer-grid h3 {
  color: #fff;
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 14px;
}
.footer-grid ul { list-style: none; margin: 0; padding: 0; }
.footer-grid li { margin-bottom: 10px; }
.footer-grid a {
  color: #fff;
  text-decoration: none;
  font-size: 15px;
  display: inline-flex;
  align-items: center;
  gap: 6px;
}
.footer-grid a:hover { color: var(--brand-300); }
.footer-info p { color: var(--gray-400); font-size: 14px; line-height: 1.8; }
.footer-info a { color: #fff; font-size: 14px; }

.footer-bottom {
  border-top: 1px solid rgba(255, 255, 255, .12);
  padding: 24px 0 32px;
}
.footer-bottom h4 {
  color: var(--gray-400);
  font-size: 13px;
  font-weight: 600;
  margin-bottom: 8px;
}
.footer-disclaimer-details summary {
  color: var(--gray-400);
  font-size: 13px;
  font-weight: 600;
  cursor: pointer;
  list-style: none;
  padding: 4px 0;
  margin-bottom: 8px;
}
.footer-disclaimer-details summary::-webkit-details-marker { display: none; }
.footer-disclaimer-details summary::before {
  content: "+";
  display: inline-block;
  width: 1.2em;
  color: var(--gray-400);
}
.footer-disclaimer-details[open] summary::before { content: "−"; }
.footer-disclaimer-details summary:hover { color: #fff; }
.footer-disclaimer {
  color: var(--gray-400);
  font-size: 13px;
  line-height: 1.8;
  max-width: 960px;
  margin-bottom: 12px;
}
.footer-copyright { color: var(--gray-400); font-size: 13px; }

@media (min-width: 769px) {
  .footer-grid { grid-template-columns: repeat(3, 1fr); gap: 48px; }
}

/* ---------- 16. 返回顶部（F3） ---------- */
.back-to-top {
  position: fixed;
  right: 24px;
  bottom: 24px;
  z-index: 150;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: #fff;
  border: 1px solid var(--gray-300);
  color: var(--brand-700);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transition: opacity .2s, background-color .15s;
}
.back-to-top.show { opacity: 1; visibility: visible; }
.back-to-top:hover { background: var(--brand-50); }

/* ---------- 17. 吸顶锚点导航（features） ---------- */
.anchor-nav {
  position: sticky;
  top: var(--header-h);
  z-index: 90;
  background: #fff;
  border-bottom: 1px solid var(--gray-200);
}
.anchor-nav ul {
  display: flex;
  gap: 8px;
  list-style: none;
  margin: 0;
  padding: 10px 16px;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}
.anchor-nav a {
  display: inline-flex;
  align-items: center;
  white-space: nowrap;
  padding: 7px 14px;
  border: 1px solid var(--gray-200);
  border-radius: var(--radius-pill);
  font-size: 14px;
  font-weight: 500;
  color: var(--gray-600);
  text-decoration: none;
  transition: color .15s, background-color .15s, border-color .15s;
}
.anchor-nav a:hover { color: var(--brand-700); }
.anchor-nav a.active {
  background: var(--brand-50);
  border-color: var(--brand-200);
  color: var(--brand-700);
  font-weight: 600;
}
@media (min-width: 769px) {
  .anchor-nav ul { justify-content: center; padding: 12px 24px; }
}

/* ---------- 18. 图片 figure ---------- */
.figure {
  border: 1px solid var(--gray-200);
  border-radius: var(--radius-l);
  padding: 8px;
  background: #fff;
}
.figure img {
  display: block;
  width: 100%;
  border-radius: calc(var(--radius-l) - 4px);
}
.figure figcaption {
  padding: 10px 8px 4px;
  color: var(--gray-500);
  font-size: 13px;
  text-align: center;
}

/* ---------- 19. 杂项 ---------- */
.mt-16 { margin-top: 16px; }
.mt-24 { margin-top: 24px; }
.mt-40 { margin-top: 40px; }
.mt-8 { margin-top: 8px; }
.text-center { text-align: center; }

.word-break { word-break: break-all; }

.divider { border: none; border-top: 1px solid var(--gray-200); margin: 0; }

/* 版本卡（download） */
.version-card {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 12px 24px;
  background: #fff;
  border: var(--border);
  border-radius: var(--radius-l);
  padding: 24px;
}
.version-card .ver-num { font-size: 28px; font-weight: 700; color: var(--brand-700); font-family: var(--font-mono); }
.version-card .ver-meta { color: var(--gray-600); font-size: 15px; }

/* 下载包卡（download） */
.package-card {
  background: #fff;
  border: var(--border);
  border-radius: var(--radius-l);
  padding: 28px 24px;
  display: flex;
  flex-direction: column;
  gap: 12px;
}
.package-card .card-icon { margin-bottom: 4px; }
.package-card h3 { font-size: 20px; }
.package-card .file-name {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: var(--gray-100);
  border-radius: var(--radius-s);
  padding: 6px 12px;
  font-family: var(--font-mono);
  font-size: 14px;
  color: var(--gray-800);
  word-break: break-all;
}
.package-card p { color: var(--gray-600); font-size: 15px; }
.package-card .btn { margin-top: 8px; }

/* 评价引用小区块（index） */
.quote-box {
  border-left: 4px solid var(--brand-200);
  background: #fff;
  border-radius: 0 var(--radius-m) var(--radius-m) 0;
  padding: 18px 22px;
  color: var(--gray-600);
  font-size: 15px;
  max-width: 760px;
}
.quote-box .src { display: block; margin-top: 6px; font-size: 13px; color: var(--gray-500); }

/* ---------- 20. 宽屏版式（消灭右侧空档） ---------- */

/* 文档型单列：正文列居中，左右留白对称 */
.doc { max-width: 900px; }
.doc .faq-list { max-width: none; }

/* 图文双栏：左文右图，.flip 交换顺序 */
.split { display: grid; gap: 28px; align-items: start; }
.split > * { min-width: 0; }
.split-media { margin: 0 auto; max-width: 340px; }
@media (min-width: 1024px) {
  .split { grid-template-columns: minmax(0, 1fr) 340px; gap: 56px; }
  .split.flip > .split-media { order: -1; }
  .split.flip { grid-template-columns: 340px minmax(0, 1fr); }
}
@media (min-width: 1100px) {
  .split-wide { grid-template-columns: minmax(0, 1fr) 380px; }
}

/* 右侧堆叠栏：提示条 / 评分卡纵向排列 */
.stack { display: grid; gap: 16px; align-content: start; }
.stack > .callout,
.stack > .quote-box { margin: 0; }

/* 横向卡片：图标在左，标题与描述在右（用于场景等 4 条内容） */
.card-row {
  display: grid;
  grid-template-columns: 48px minmax(0, 1fr);
  column-gap: 18px;
  row-gap: 4px;
  align-content: center;
}
.card-row .card-icon { grid-row: 1 / span 2; align-self: center; margin: 0; }
.card-row .card-title { grid-column: 2; margin: 0; font-size: 18px; }
.card-row .card-desc { grid-column: 2; }

/* 强调磁贴：补齐网格空位 + 引导内链 */
.card-cta {
  background: var(--brand-50);
  border-color: var(--brand-200);
}
.card-cta .card-icon { background: #fff; color: var(--brand-700); }
.card-cta:hover { border-color: var(--brand-400); }
.card-cta .card-desc { color: var(--brand-900); }

/* 两列勾选清单 */
@media (min-width: 900px) {
  .check-list-2 {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    column-gap: 48px;
    max-width: none;
  }
  .check-list-2 li:nth-child(odd):nth-last-child(1) { grid-column: 1 / -1; }
}

/* 参数卡（features 模块右侧） */
.spec-card {
  background: #fff;
  border: var(--border);
  border-radius: var(--radius-l);
  padding: 22px 24px;
}
/* 锚点命中时给卡片一点反馈 */
.card:target,
.spec-card:target { border-color: var(--brand-300); }
.spec-title {
  font-size: 15px;
  font-weight: 600;
  color: var(--brand-700);
  margin-bottom: 4px;
  display: flex;
  align-items: center;
  gap: 8px;
}
.spec-title::before {
  content: "";
  width: 3px;
  height: 14px;
  border-radius: 2px;
  background: var(--brand-500);
}
.spec-list { margin: 0; padding: 0; }
.spec-list > div {
  display: grid;
  grid-template-columns: 96px minmax(0, 1fr);
  gap: 12px;
  padding: 10px 0;
  border-top: 1px solid var(--gray-100);
  font-size: 14px;
}
.spec-list > div:first-child { border-top: none; }
.spec-list dt { color: var(--gray-500); }
.spec-list dd { margin: 0; color: var(--gray-800); }

/* 星级评分 */
.stars { display: flex; gap: 3px; color: #D99B1E; margin-bottom: 8px; }
.stars svg { flex-shrink: 0; }

/* 标题内嵌徽章 */
.h2-inline { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; }

/* 版本要点面板（features v4.0） */
.v4-panel {
  display: grid;
  gap: 24px;
  background: #fff;
  border: var(--border);
  border-radius: var(--radius-l);
  padding: 26px 28px;
}
.v4-panel .prose { max-width: none; }
@media (min-width: 900px) {
  .v4-panel { grid-template-columns: minmax(0, 1fr) auto; align-items: center; gap: 40px; }
  .v4-panel .prose ul { columns: 2; column-gap: 36px; }
  .v4-panel .prose li { break-inside: avoid; }
}
.v4-cta { display: grid; gap: 8px; justify-items: start; }
.v4-cta .small-note { font-size: 13px; color: var(--gray-500); }
@media (min-width: 900px) {
  .v4-cta { justify-items: center; text-align: center; padding-left: 32px; border-left: 1px solid var(--gray-200); }
  .v4-cta .small-note { max-width: 220px; }
}

/* ---------- 21. 动效偏好 ---------- */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: .01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: .01ms !important;
    scroll-behavior: auto !important;
  }
}