/* ============================================================
   糖心小桃 · 全站样式表
   技术工作台风：中性底色、深灰正文、强调蓝、紧凑界面
   ============================================================ */

/* ============================================================
   Base —— 基础样式、变量、重置、全局排版
   ============================================================ */

:root {
  --color-bg: #f5f6f8;
  --color-text: #1f2933;
  --color-text-secondary: #52606d;
  --color-text-muted: #7b8794;
  --color-primary: #2563eb;
  --color-primary-hover: #1d4ed8;
  --color-primary-light: #eff4ff;
  --color-border: #e5e7eb;
  --color-success: #10b981;
  --color-success-light: #ecfdf5;
  --color-white: #ffffff;
  --color-card-bg: #ffffff;
  --color-code-bg: #f3f4f6;

  --font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", sans-serif;

  --font-size-h1: 28px;
  --font-size-h2: 22px;
  --font-size-h3: 18px;
  --font-size-body: 15px;
  --font-size-small: 13px;
  --font-size-xs: 12px;

  --radius-sm: 4px;
  --radius-md: 6px;
  --radius-lg: 8px;

  --header-height: 64px;
  --container-width: 1200px;
  --content-max-width: 1200px;

  --space-1: 4px;
  --space-2: 8px;
  --space-3: 12px;
  --space-4: 16px;
  --space-5: 20px;
  --space-6: 24px;
  --space-7: 32px;
  --space-8: 40px;
  --space-9: 48px;
  --space-10: 56px;
}

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

html {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-family);
  font-size: var(--font-size-body);
  line-height: 1.7;
  color: var(--color-text);
  background-color: var(--color-bg);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

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

a {
  color: var(--color-primary);
  text-decoration: none;
  transition: color 0.2s ease;
}

a:hover {
  color: var(--color-primary-hover);
  text-decoration: underline;
}

ul,
ol {
  list-style: none;
}

button {
  font-family: inherit;
  border: none;
  background: none;
  cursor: pointer;
  color: inherit;
}

table {
  border-collapse: collapse;
  width: 100%;
}

/* 滚动渐显动画 —— 仅作为增强，不影响初始可见性 */
.reveal {
  opacity: 1;
  transform: none;
}

@media (prefers-reduced-motion: no-preference) {
  .reveal {
    transition: opacity 0.4s ease, transform 0.4s ease;
  }
}

/* ============================================================
   Layout —— 全站布局骨架：页头、页脚、容器、主区域
   ============================================================ */

.site-body {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.site-main {
  flex: 1 0 auto;
  width: 100%;
}

/* 页头 */
.site-header {
  background-color: var(--color-white);
  border-bottom: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  z-index: 100;
}

.header-shell {
  max-width: var(--container-width);
  margin: 0 auto;
  padding: 0 24px;
  height: var(--header-height);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

/* 品牌 */
.brand {
  flex-shrink: 0;
}

.brand-link {
  display: flex;
  align-items: baseline;
  gap: 8px;
  text-decoration: none;
}

.brand-link:hover {
  text-decoration: none;
}

.brand-name {
  font-size: 20px;
  font-weight: 700;
  color: var(--color-text);
  letter-spacing: 0.01em;
}

.brand-slogan {
  font-size: var(--font-size-xs);
  color: var(--color-text-muted);
  letter-spacing: 0.02em;
}

/* 主导航 */
.site-nav {
  display: flex;
  align-items: center;
}

.nav-list {
  display: flex;
  align-items: center;
  gap: 2px;
}

.nav-item {
  position: relative;
}

.nav-link {
  display: block;
  padding: 8px 14px;
  font-size: var(--font-size-body);
  color: var(--color-text-secondary);
  border-radius: var(--radius-sm);
  transition: color 0.2s ease, background-color 0.2s ease;
}

.nav-link:hover {
  color: var(--color-primary);
  background-color: var(--color-primary-light);
  text-decoration: none;
}

.nav-link.is-current {
  color: var(--color-primary);
  font-weight: 600;
  background-color: var(--color-primary-light);
}

/* 汉堡按钮（默认隐藏，移动端显示） */
.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 5px;
  width: 44px;
  height: 44px;
  padding: 0;
  border-radius: var(--radius-sm);
  background: transparent;
}

.nav-toggle:hover {
  background-color: var(--color-bg);
}

.nav-toggle-bar {
  display: block;
  width: 22px;
  height: 2px;
  background-color: var(--color-text);
  border-radius: 1px;
  transition: transform 0.2s ease, opacity 0.2s ease;
}

/* 页脚 */
.site-footer {
  background-color: var(--color-white);
  border-top: 1px solid var(--color-border);
  margin-top: auto;
  flex-shrink: 0;
}

.footer-shell {
  max-width: var(--container-width);
  margin: 0 auto;
  padding: 40px 24px 24px;
  display: grid;
  grid-template-columns: 2fr 1fr;
  gap: 40px;
}

.footer-brand {
  font-size: var(--font-size-h3);
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: 8px;
}

.footer-desc {
  font-size: var(--font-size-body);
  color: var(--color-text-secondary);
  line-height: 1.7;
  max-width: 420px;
}

.footer-nav-title {
  font-size: var(--font-size-body);
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: 12px;
}

.footer-nav-list {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.footer-nav-list a {
  font-size: var(--font-size-body);
  color: var(--color-text-secondary);
}

.footer-nav-list a:hover {
  color: var(--color-primary);
}

.footer-bottom {
  border-top: 1px solid var(--color-border);
  padding: 16px 24px;
  text-align: center;
}

.footer-bottom p {
  font-size: var(--font-size-small);
  color: var(--color-text-muted);
  max-width: var(--container-width);
  margin: 0 auto;
}

/* 内页主容器 */
.inner-main {
  max-width: var(--container-width);
  margin: 0 auto;
  padding: 0 24px 56px;
  width: 100%;
  flex: 1 0 auto;
}

/* 面包屑 */
.breadcrumb {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 6px;
  padding: 20px 0 12px;
  font-size: var(--font-size-small);
  color: var(--color-text-muted);
}

.breadcrumb a {
  color: var(--color-text-secondary);
}

.breadcrumb a:hover {
  color: var(--color-primary);
}

.breadcrumb-sep {
  color: var(--color-text-muted);
  margin: 0 2px;
}

.breadcrumb-current {
  color: var(--color-text);
  font-weight: 500;
}

/* 页面标题区 */
.page-header {
  padding: 8px 0 24px;
  border-bottom: 1px solid var(--color-border);
  margin-bottom: 28px;
}

.page-title {
  font-size: var(--font-size-h1);
  font-weight: 700;
  color: var(--color-text);
  line-height: 1.4;
  margin-bottom: 8px;
}

.page-description {
  font-size: var(--font-size-body);
  color: var(--color-text-secondary);
  line-height: 1.7;
  max-width: 780px;
}

/* 通用区块标题 */
.section-title {
  font-size: var(--font-size-h2);
  font-weight: 700;
  color: var(--color-text);
  line-height: 1.4;
  margin-bottom: 8px;
}

.section-desc {
  font-size: var(--font-size-body);
  color: var(--color-text-secondary);
  line-height: 1.7;
  margin-bottom: 20px;
  max-width: 720px;
}

.section-intro {
  font-size: var(--font-size-body);
  color: var(--color-text-secondary);
  line-height: 1.7;
  margin-bottom: 20px;
  max-width: 720px;
}

/* 侧栏标题 */
.sidebar-title,
.aside-title {
  font-size: var(--font-size-h3);
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: 16px;
  padding-bottom: 8px;
  border-bottom: 2px solid var(--color-primary);
}

/* 通用页面布局（主内容 + 右侧栏） */
.page-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 300px;
  gap: 32px;
  align-items: start;
}

.layout-shell {
  width: 100%;
}

/* ============================================================
   Components —— 通用组件：按钮、卡片、标签、表格、FAQ 等
   ============================================================ */

/* 按钮 */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 10px 24px;
  font-size: var(--font-size-body);
  font-weight: 600;
  border-radius: var(--radius-md);
  transition: background-color 0.2s ease, color 0.2s ease, border-color 0.2s ease;
  cursor: pointer;
  text-decoration: none;
  min-height: 44px;
}

.btn:hover {
  text-decoration: none;
}

.btn-primary {
  background-color: var(--color-primary);
  color: var(--color-white);
  border: 1px solid var(--color-primary);
}

.btn-primary:hover {
  background-color: var(--color-primary-hover);
  border-color: var(--color-primary-hover);
  color: var(--color-white);
}

.btn-secondary {
  background-color: var(--color-white);
  color: var(--color-primary);
  border: 1px solid var(--color-border);
}

.btn-secondary:hover {
  border-color: var(--color-primary);
  background-color: var(--color-primary-light);
  color: var(--color-primary);
}

/* 首页区块通用 */
.section-block {
  padding: 48px 24px;
  max-width: var(--container-width);
  margin: 0 auto;
  width: 100%;
}

.section-block + .section-block {
  border-top: 1px solid var(--color-border);
}

.section-heading {
  margin-bottom: 24px;
}

/* 分类卡片（首页） */
.category-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
}

.category-card {
  background-color: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 20px;
  display: flex;
  flex-direction: column;
  gap: 10px;
  transition: box-shadow 0.2s ease, border-color 0.2s ease;
  min-height: 160px;
}

.category-card:hover {
  box-shadow: 0 2px 8px rgba(31, 41, 51, 0.08);
  border-color: var(--color-primary);
}

.category-icon {
  width: 40px;
  height: 40px;
  object-fit: contain;
  border-radius: var(--radius-sm);
}

.category-name {
  font-size: var(--font-size-h3);
  font-weight: 600;
  color: var(--color-text);
  line-height: 1.4;
}

.category-desc {
  font-size: var(--font-size-body);
  color: var(--color-text-secondary);
  line-height: 1.6;
  flex: 1;
}

.category-link {
  font-size: var(--font-size-small);
  font-weight: 600;
  color: var(--color-primary);
  align-self: flex-start;
}

.category-link::after {
  content: " →";
}

/* 编辑推荐卡片 */
.featured-list {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
}

.featured-card {
  background-color: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 20px;
  display: flex;
  flex-direction: column;
  gap: 10px;
  transition: box-shadow 0.2s ease, border-color 0.2s ease;
}

.featured-card:hover {
  box-shadow: 0 2px 8px rgba(31, 41, 51, 0.08);
  border-color: var(--color-primary);
}

.featured-content {
  display: flex;
  flex-direction: column;
  gap: 8px;
  flex: 1;
}

.featured-title {
  font-size: var(--font-size-h3);
  font-weight: 600;
  color: var(--color-text);
  line-height: 1.4;
}

.featured-summary {
  font-size: var(--font-size-body);
  color: var(--color-text-secondary);
  line-height: 1.6;
  flex: 1;
}

.featured-link {
  font-size: var(--font-size-small);
  font-weight: 600;
  color: var(--color-primary);
  align-self: flex-start;
}

.featured-link::after {
  content: " →";
}

/* 步骤条（首页） */
.guide-steps {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
  counter-reset: step-counter;
}

.step-item {
  background-color: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 20px;
  display: flex;
  flex-direction: column;
  gap: 10px;
  position: relative;
  min-height: 140px;
}

.step-number {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  border-radius: 50%;
  background-color: var(--color-primary);
  color: var(--color-white);
  font-size: var(--font-size-body);
  font-weight: 700;
  flex-shrink: 0;
}

.step-title {
  font-size: var(--font-size-h3);
  font-weight: 600;
  color: var(--color-text);
  line-height: 1.4;
}

.step-desc {
  font-size: var(--font-size-body);
  color: var(--color-text-secondary);
  line-height: 1.6;
}

.guide-more {
  display: inline-block;
  margin-top: 20px;
  font-size: var(--font-size-body);
  font-weight: 600;
  color: var(--color-primary);
}

.guide-more::after {
  content: " →";
}

/* 标准摘要（首页） */
.standards-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
}

.standard-item {
  background-color: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 20px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.standard-title {
  font-size: var(--font-size-h3);
  font-weight: 600;
  color: var(--color-text);
  line-height: 1.4;
}

.standard-text {
  font-size: var(--font-size-body);
  color: var(--color-text-secondary);
  line-height: 1.6;
  flex: 1;
}

.standard-link {
  font-size: var(--font-size-small);
  font-weight: 600;
  color: var(--color-primary);
  align-self: flex-start;
}

.standard-link::after {
  content: " →";
}

/* FAQ 入口（首页） */
.faq-entry-list {
  display: flex;
  flex-direction: column;
  gap: 8px;
  max-width: 720px;
}

.faq-entry-item {
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  background-color: var(--color-card-bg);
}

.faq-entry-link {
  display: block;
  padding: 14px 16px;
  font-size: var(--font-size-body);
  color: var(--color-text);
  transition: color 0.2s ease, border-color 0.2s ease;
}

.faq-entry-link:hover {
  color: var(--color-primary);
  text-decoration: none;
}

.faq-entry-link::after {
  content: " →";
  margin-left: 4px;
  color: var(--color-primary);
}

.faq-more {
  display: inline-block;
  margin-top: 16px;
  font-size: var(--font-size-body);
  font-weight: 600;
  color: var(--color-primary);
}

.faq-more::after {
  content: " →";
}

/* 语义表格（内容标准页） */
.rule-table__grid {
  width: 100%;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  overflow: hidden;
  font-size: var(--font-size-body);
}

.rule-table__grid thead {
  background-color: var(--color-code-bg);
}

.rule-table__grid th {
  text-align: left;
  padding: 12px 16px;
  font-weight: 600;
  color: var(--color-text);
  border-bottom: 2px solid var(--color-border);
  white-space: nowrap;
}

.rule-table__grid td {
  padding: 12px 16px;
  border-bottom: 1px solid var(--color-border);
  color: var(--color-text-secondary);
  line-height: 1.6;
  vertical-align: top;
}

.rule-table__grid tbody tr:last-child td {
  border-bottom: none;
}

.rule-table__grid tbody tr:hover {
  background-color: var(--color-bg);
}

/* 折叠 FAQ（疑问解答页） */
.faq-item {
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  background-color: var(--color-card-bg);
  margin-bottom: 12px;
  overflow: hidden;
}

.faq-item summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 20px;
  font-size: var(--font-size-body);
  font-weight: 600;
  color: var(--color-text);
  cursor: pointer;
  list-style: none;
  transition: background-color 0.2s ease;
  min-height: 48px;
}

.faq-item summary::-webkit-details-marker {
  display: none;
}

.faq-item summary::after {
  content: "+";
  font-size: 20px;
  color: var(--color-primary);
  font-weight: 400;
  transition: transform 0.2s ease;
  flex-shrink: 0;
  margin-left: 12px;
}

.faq-item[open] summary::after {
  transform: rotate(45deg);
}

.faq-item summary:hover {
  background-color: var(--color-bg);
}

.faq-answer {
  padding: 0 20px 16px;
  font-size: var(--font-size-body);
  color: var(--color-text-secondary);
  line-height: 1.7;
  border-top: 1px solid var(--color-border);
  padding-top: 12px;
}

.faq-answer p {
  margin-bottom: 8px;
}

.faq-answer p:last-child {
  margin-bottom: 0;
}

/* 标签链接（视频索引页） */
.tag-group {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.tag-link {
  display: inline-block;
  padding: 6px 16px;
  font-size: var(--font-size-small);
  font-weight: 500;
  color: var(--color-text-secondary);
  background-color: var(--color-white);
  border: 1px solid var(--color-border);
  border-radius: 999px;
  transition: color 0.2s ease, border-color 0.2s ease, background-color 0.2s ease;
  min-height: 32px;
  line-height: 1.4;
}

.tag-link:hover {
  color: var(--color-primary);
  border-color: var(--color-primary);
  background-color: var(--color-primary-light);
  text-decoration: none;
}

/* 图片容器 */
figure {
  margin: 0;
}

figcaption {
  font-size: var(--font-size-small);
  color: var(--color-text-muted);
  text-align: center;
  padding: 8px 0 0;
  line-height: 1.5;
}

/* ============================================================
   Pages —— 首页与各内页专属模块
   ============================================================ */

/* ---------- 首页 ---------- */

.home-main {
  width: 100%;
}

/* 首屏 hero */
.hero-section {
  background-color: var(--color-white);
  border-bottom: 1px solid var(--color-border);
}

.hero-section {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 40px;
  align-items: center;
  max-width: var(--container-width);
  margin: 0 auto;
  padding: 48px 24px 56px;
}

.hero-copy {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.hero-title {
  font-size: 32px;
  font-weight: 700;
  color: var(--color-text);
  line-height: 1.3;
}

.hero-lead {
  font-size: var(--font-size-body);
  color: var(--color-text-secondary);
  line-height: 1.7;
  max-width: 520px;
}

.hero-actions {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
}

.hero-media {
  border-radius: var(--radius-lg);
  overflow: hidden;
  border: 1px solid var(--color-border);
}

.hero-media img {
  width: 100%;
  height: 320px;
  object-fit: cover;
}

/* 首页分类卡片（复用 category-grid，但首页卡片无媒体图） */
/* 首页分类卡片图标样式 */
.category-overview .category-card {
  padding: 20px;
}

.category-overview .category-icon {
  width: 40px;
  height: 40px;
  object-fit: contain;
}

/* 首页编辑推荐区 */
.featured-topics .featured-card {
  background-color: var(--color-card-bg);
}

/* 首页指引步骤 */
.guide-preview .step-item {
  background-color: var(--color-card-bg);
}

/* 首页 FAQ 入口 */
.faq-entry .section-heading {
  margin-bottom: 20px;
}

/* ---------- 内容分区页（sections） ---------- */

.page-sections .category-overview {
  margin-bottom: 40px;
}

.page-sections .category-grid {
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
}

.page-sections .category-card {
  padding: 0;
  overflow: hidden;
  background-color: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  transition: box-shadow 0.2s ease, border-color 0.2s ease;
}

.page-sections .category-card:hover {
  box-shadow: 0 2px 8px rgba(31, 41, 51, 0.08);
  border-color: var(--color-primary);
}

.page-sections .category-card-media {
  width: 100%;
  height: 140px;
  overflow: hidden;
}

.page-sections .category-card-media img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.page-sections .category-card-body {
  padding: 16px;
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.page-sections .category-card-title {
  font-size: var(--font-size-h3);
  font-weight: 600;
  color: var(--color-text);
  line-height: 1.4;
}

.page-sections .category-card-desc {
  font-size: var(--font-size-body);
  color: var(--color-text-secondary);
  line-height: 1.6;
}

/* 分区详细说明 */
.detail-list {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.detail-item {
  background-color: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 20px;
  display: grid;
  grid-template-columns: 48px 1fr;
  gap: 16px;
}

.detail-item-head {
  display: flex;
  align-items: flex-start;
  gap: 12px;
}

.detail-item-index {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: var(--radius-md);
  background-color: var(--color-primary-light);
  color: var(--color-primary);
  font-size: var(--font-size-h3);
  font-weight: 700;
  flex-shrink: 0;
}

.detail-item-title {
  font-size: var(--font-size-h3);
  font-weight: 600;
  color: var(--color-text);
  line-height: 1.4;
  padding-top: 4px;
}

.detail-item-body {
  grid-column: 2;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.detail-item-text {
  font-size: var(--font-size-body);
  color: var(--color-text-secondary);
  line-height: 1.7;
}

.detail-item-audience {
  font-size: var(--font-size-small);
  color: var(--color-text-secondary);
  background-color: var(--color-bg);
  padding: 8px 12px;
  border-radius: var(--radius-sm);
  line-height: 1.6;
}

.detail-item-audience strong {
  color: var(--color-text);
  font-weight: 600;
  margin-right: 4px;
}

/* 分区桥接区块 */
.section-bridge {
  margin-top: 40px;
  padding: 24px;
  background-color: var(--color-primary-light);
  border-radius: var(--radius-lg);
  border: 1px solid var(--color-primary);
}

.section-bridge-link a {
  font-weight: 600;
}

.section-bridge-link a::after {
  content: " →";
}

/* 侧栏范围说明 */
.sidebar-note {
  background-color: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 20px;
  margin-top: 24px;
}

.sidebar-text {
  font-size: var(--font-size-body);
  color: var(--color-text-secondary);
  line-height: 1.7;
  margin-bottom: 12px;
}

.sidebar-text:last-child {
  margin-bottom: 0;
}

/* ---------- 视频索引页（videos） ---------- */

.page-videos .page-layout {
  grid-template-columns: minmax(0, 1fr) 280px;
  gap: 32px;
}

/* 筛选标签 */
.filter-tags {
  margin-bottom: 32px;
}

.tag-group {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

/* 视频分组 */
.video-group {
  margin-bottom: 32px;
}

.group-title {
  font-size: var(--font-size-h3);
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: 12px;
  padding-bottom: 8px;
  border-bottom: 2px solid var(--color-border);
  display: flex;
  align-items: center;
  gap: 8px;
}

.group-title::before {
  content: "";
  display: inline-block;
  width: 4px;
  height: 18px;
  background-color: var(--color-primary);
  border-radius: 2px;
}

/* 视频条目 */
.video-item {
  display: grid;
  grid-template-columns: 120px 1fr;
  gap: 16px;
  padding: 12px 0;
  border-bottom: 1px solid var(--color-border);
  align-items: start;
}

.video-item:last-child {
  border-bottom: none;
}

.video-thumb {
  width: 120px;
  height: 80px;
  border-radius: var(--radius-sm);
  overflow: hidden;
  background-color: var(--color-code-bg);
  border: 1px solid var(--color-border);
}

.video-thumb img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.video-info {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.video-name {
  font-size: var(--font-size-body);
  font-weight: 600;
  color: var(--color-text);
  line-height: 1.4;
}

.video-tag {
  display: inline-block;
  font-size: var(--font-size-xs);
  color: var(--color-primary);
  background-color: var(--color-primary-light);
  padding: 2px 8px;
  border-radius: 999px;
  align-self: flex-start;
  line-height: 1.5;
}

.video-theme {
  font-size: var(--font-size-small);
  color: var(--color-text-secondary);
  line-height: 1.6;
}

.video-audience {
  font-size: var(--font-size-small);
  color: var(--color-text-muted);
  line-height: 1.6;
}

/* 侧栏 */
.aside-list {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.aside-list li {
  border-bottom: 1px solid var(--color-border);
}

.aside-list li:last-child {
  border-bottom: none;
}

.aside-list a {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px 8px;
  font-size: var(--font-size-body);
  color: var(--color-text-secondary);
  border-radius: var(--radius-sm);
  transition: color 0.2s ease, background-color 0.2s ease;
}

.aside-list a:hover {
  color: var(--color-primary);
  background-color: var(--color-primary-light);
  text-decoration: none;
}

.count {
  font-size: var(--font-size-xs);
  color: var(--color-text-muted);
  background-color: var(--color-bg);
  padding: 2px 8px;
  border-radius: 999px;
}

.aside-note {
  font-size: var(--font-size-small);
  color: var(--color-text-muted);
  line-height: 1.6;
  margin-top: 16px;
  padding: 12px;
  background-color: var(--color-bg);
  border-radius: var(--radius-sm);
}

/* 相关链接 */
.related-links {
  margin-top: 40px;
  padding-top: 24px;
  border-top: 1px solid var(--color-border);
}

.related-links-label {
  font-size: var(--font-size-small);
  color: var(--color-text-muted);
  margin-right: 12px;
}

.related-links-item {
  font-size: var(--font-size-body);
  color: var(--color-primary);
  margin-right: 16px;
}

.related-links-item:hover {
  text-decoration: underline;
}

/* ---------- 专题策划页（features） ---------- */

.page-features .page-layout {
  grid-template-columns: minmax(0, 1fr) 280px;
  gap: 32px;
}

.feature-list {
  display: flex;
  flex-direction: column;
  gap: 24px;
}

.feature-card {
  background-color: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  display: grid;
  grid-template-columns: 240px 1fr;
  transition: box-shadow 0.2s ease;
}

.feature-card:hover {
  box-shadow: 0 2px 8px rgba(31, 41, 51, 0.08);
}

.feature-media {
  background-color: var(--color-code-bg);
}

.feature-figure {
  width: 100%;
  height: 100%;
  min-height: 180px;
}

.feature-figure img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.feature-body {
  padding: 20px;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.feature-tag {
  display: inline-block;
  font-size: var(--font-size-xs);
  font-weight: 600;
  color: var(--color-primary);
  background-color: var(--color-primary-light);
  padding: 4px 10px;
  border-radius: 999px;
  align-self: flex-start;
  line-height: 1.4;
}

.feature-name {
  font-size: var(--font-size-h3);
  font-weight: 600;
  color: var(--color-text);
  line-height: 1.4;
}

.feature-summary {
  font-size: var(--font-size-body);
  color: var(--color-text-secondary);
  line-height: 1.7;
}

.feature-detail {
  font-size: var(--font-size-body);
  color: var(--color-text-secondary);
  line-height: 1.7;
}

.feature-detail p {
  margin-bottom: 8px;
}

.feature-detail p:last-child {
  margin-bottom: 0;
}

.feature-link {
  font-size: var(--font-size-small);
  font-weight: 600;
  color: var(--color-primary);
  align-self: flex-start;
}

.feature-link::after {
  content: " →";
}

/* 专题说明 */
.feature-note {
  margin-top: 24px;
  padding: 20px;
  background-color: var(--color-bg);
  border-radius: var(--radius-md);
  border: 1px solid var(--color-border);
}

.feature-note p {
  font-size: var(--font-size-body);
  color: var(--color-text-secondary);
  line-height: 1.7;
}

/* 侧栏标签 */
.sidebar-tag-list {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.sidebar-tag-item a {
  display: block;
  padding: 10px 12px;
  font-size: var(--font-size-body);
  color: var(--color-text-secondary);
  border-radius: var(--radius-sm);
  border-left: 3px solid transparent;
  transition: color 0.2s ease, background-color 0.2s ease, border-color 0.2s ease;
}

.sidebar-tag-item a:hover {
  color: var(--color-primary);
  background-color: var(--color-primary-light);
  border-left-color: var(--color-primary);
  text-decoration: none;
}

.sidebar-note {
  font-size: var(--font-size-small);
  color: var(--color-text-muted);
  line-height: 1.6;
  margin-top: 16px;
  padding: 12px;
  background-color: var(--color-bg);
  border-radius: var(--radius-sm);
}

.sidebar-guide {
  margin-top: 16px;
  font-size: var(--font-size-small);
}

.sidebar-guide a {
  font-weight: 600;
}

/* ---------- 观看手册页（guide） ---------- */

.page-guide .page-layout {
  grid-template-columns: minmax(0, 1fr) 260px;
  gap: 40px;
}

.guide-steps {
  display: flex;
  flex-direction: column;
  gap: 0;
  counter-reset: none;
}

.guide-steps .step-item {
  background-color: transparent;
  border: none;
  border-left: 3px solid var(--color-border);
  border-radius: 0;
  padding: 0 0 24px 24px;
  position: relative;
  min-height: 0;
}

.guide-steps .step-item::before {
  content: "";
  position: absolute;
  left: -7px;
  top: 4px;
  width: 11px;
  height: 11px;
  border-radius: 50%;
  background-color: var(--color-primary);
  border: 2px solid var(--color-white);
}

.guide-steps .step-item:last-child {
  border-left-color: transparent;
  padding-bottom: 0;
}

.guide-steps .step-number {
  position: static;
  display: inline-flex;
  width: auto;
  height: auto;
  background-color: transparent;
  color: var(--color-primary);
  font-size: var(--font-size-small);
  font-weight: 700;
  margin-bottom: 4px;
}

.step-body {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.step-body h3 {
  font-size: var(--font-size-h3);
  font-weight: 600;
  color: var(--color-text);
  line-height: 1.4;
}

.step-body p {
  font-size: var(--font-size-body);
  color: var(--color-text-secondary);
  line-height: 1.7;
}

.step-body a {
  font-weight: 600;
}

/* 引导配图 */
.guide-media {
  margin-top: 32px;
  border-radius: var(--radius-lg);
  overflow: hidden;
  border: 1px solid var(--color-border);
  background-color: var(--color-white);
}

.guide-media img {
  width: 100%;
  height: 240px;
  object-fit: cover;
}

/* 使用提示 */
.guide-tips {
  margin-top: 32px;
  padding: 24px;
  background-color: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
}

.tip-list {
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin: 16px 0;
}

.tip-list li {
  font-size: var(--font-size-body);
  color: var(--color-text-secondary);
  line-height: 1.7;
  padding-left: 20px;
  position: relative;
}

.tip-list li::before {
  content: "·";
  position: absolute;
  left: 4px;
  color: var(--color-primary);
  font-weight: 700;
}

.guide-tips a {
  font-weight: 600;
}

/* FAQ 入口 */
.guide-faq-entry {
  margin-top: 32px;
  padding: 24px;
  background-color: var(--color-primary-light);
  border-radius: var(--radius-lg);
  border: 1px solid var(--color-primary);
}

.guide-faq-entry h2 {
  font-size: var(--font-size-h3);
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: 8px;
}

.guide-faq-entry p {
  font-size: var(--font-size-body);
  color: var(--color-text-secondary);
  line-height: 1.7;
  margin-bottom: 8px;
}

.guide-faq-entry a {
  font-weight: 600;
}

/* 侧栏目录 */
.aside-nav-list {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.aside-nav-list li {
  border-bottom: 1px solid var(--color-border);
}

.aside-nav-list li:last-child {
  border-bottom: none;
}

.aside-nav-list a {
  display: block;
  padding: 10px 8px;
  font-size: var(--font-size-body);
  color: var(--color-text-secondary);
  border-radius: var(--radius-sm);
  border-left: 3px solid transparent;
  transition: color 0.2s ease, background-color 0.2s ease, border-color 0.2s ease;
}

.aside-nav-list a:hover {
  color: var(--color-primary);
  background-color: var(--color-primary-light);
  border-left-color: var(--color-primary);
  text-decoration: none;
}

/* ---------- 内容标准页（standards） ---------- */

.rule-table {
  margin-bottom: 40px;
}

.annotation-list {
  margin-bottom: 40px;
}

.annotation-list__items {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.annotation-item {
  background-color: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 16px 20px;
}

.annotation-item__title {
  font-size: var(--font-size-h3);
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: 6px;
  line-height: 1.4;
}

.annotation-item__text {
  font-size: var(--font-size-body);
  color: var(--color-text-secondary);
  line-height: 1.7;
}

/* 边界声明 */
.boundary-statement {
  margin-bottom: 40px;
  padding: 24px;
  background-color: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
}

.boundary-statement__content {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.boundary-statement__content p {
  font-size: var(--font-size-body);
  color: var(--color-text-secondary);
  line-height: 1.7;
}

.boundary-statement__content p:first-child {
  font-weight: 500;
  color: var(--color-text);
}

.boundary-statement__list {
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding-left: 4px;
}

.boundary-statement__list li {
  font-size: var(--font-size-body);
  color: var(--color-text-secondary);
  line-height: 1.7;
  padding-left: 20px;
  position: relative;
}

.boundary-statement__list li::before {
  content: "—";
  position: absolute;
  left: 0;
  color: var(--color-primary);
}

.boundary-statement__content p:last-child a {
  font-weight: 600;
  margin-right: 12px;
}

/* 结构示意图 */
.standards-figure {
  margin: 32px 0;
  border-radius: var(--radius-lg);
  overflow: hidden;
  border: 1px solid var(--color-border);
  background-color: var(--color-white);
}

.standards-figure__img {
  width: 100%;
  height: 280px;
  object-fit: cover;
}

/* 相关链接 */
.related-links__intro {
  font-size: var(--font-size-body);
  color: var(--color-text-secondary);
  margin-bottom: 12px;
}

.related-links__list {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 24px;
}

.related-links__list li a {
  font-weight: 500;
}

.related-links__list li a::after {
  content: " →";
}

/* ---------- 疑问解答页（help） ---------- */

.faq-list {
  margin-bottom: 40px;
}

.content-media-inline {
  margin: 0 0 24px;
  border-radius: var(--radius-lg);
  overflow: hidden;
  border: 1px solid var(--color-border);
  background-color: var(--color-white);
}

.content-media-inline img {
  width: 100%;
  height: 200px;
  object-fit: cover;
}

.feedback-note {
  padding: 24px;
  background-color: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
}

.feedback-content {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.feedback-content p {
  font-size: var(--font-size-body);
  color: var(--color-text-secondary);
  line-height: 1.7;
}

.feedback-content a {
  font-weight: 600;
}

/* ---------- 404 页 ---------- */

.error-main {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 80px 24px;
  flex: 1 0 auto;
}

.error-panel {
  text-align: center;
  max-width: 480px;
  background-color: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 48px 40px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
}

.error-code {
  font-size: 64px;
  font-weight: 700;
  color: var(--color-primary);
  line-height: 1;
}

.error-panel h1 {
  font-size: var(--font-size-h2);
  font-weight: 700;
  color: var(--color-text);
}

.error-desc {
  font-size: var(--font-size-body);
  color: var(--color-text-secondary);
  line-height: 1.7;
}

.error-btn {
  display: inline-block;
  padding: 10px 24px;
  background-color: var(--color-primary);
  color: var(--color-white);
  border-radius: var(--radius-md);
  font-weight: 600;
  min-height: 44px;
  line-height: 1.4;
}

.error-btn:hover {
  background-color: var(--color-primary-hover);
  color: var(--color-white);
  text-decoration: none;
}

.error-help {
  font-size: var(--font-size-small);
  color: var(--color-text-muted);
}

/* ============================================================
   Responsive —— 响应式断点
   ============================================================ */

/* 平板及以下 */
@media (max-width: 1024px) {
  .category-grid,
  .featured-list {
    grid-template-columns: repeat(2, 1fr);
  }

  .page-layout,
  .page-videos .page-layout,
  .page-features .page-layout,
  .page-guide .page-layout {
    grid-template-columns: 1fr;
    gap: 32px;
  }

  .layout-aside,
  .sidebar,
  .guide-aside {
    order: 2;
  }

  .hero-section {
    grid-template-columns: 1fr;
    gap: 24px;
  }

  .hero-media img {
    height: 260px;
  }

  .feature-card {
    grid-template-columns: 200px 1fr;
  }
}

/* 移动端 */
@media (max-width: 768px) {
  .header-shell {
    height: auto;
    min-height: var(--header-height);
    padding: 8px 16px;
    flex-wrap: wrap;
  }

  .brand-slogan {
    display: none;
  }

  /* 汉堡按钮显示 */
  .nav-toggle {
    display: flex;
  }

  /* 导航列表收起 */
  .site-nav {
    order: 3;
    width: 100%;
  }

  .nav-list {
    display: none;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding: 8px 0 16px;
    border-top: 1px solid var(--color-border);
    margin-top: 8px;
  }

  .nav-list.is-open {
    display: flex;
  }

  .nav-item {
    width: 100%;
  }

  .nav-link {
    padding: 12px 8px;
    font-size: var(--font-size-body);
    border-radius: var(--radius-sm);
  }

  .nav-link.is-current {
    background-color: var(--color-primary-light);
  }

  /* 容器边距 */
  .section-block {
    padding: 32px 16px;
  }

  .inner-main {
    padding: 0 16px 40px;
  }

  .footer-shell {
    grid-template-columns: 1fr;
    gap: 24px;
    padding: 32px 16px 24px;
  }

  .footer-bottom {
    padding: 12px 16px;
  }

  /* 首页分类 */
  .category-grid {
    grid-template-columns: 1fr;
    gap: 12px;
  }

  .category-card {
    min-height: 0;
  }

  /* 首页推荐专题 */
  .featured-list {
    grid-template-columns: 1fr;
    gap: 12px;
  }

  /* 首页指引步骤 */
  .guide-steps {
    grid-template-columns: 1fr;
    gap: 12px;
  }

  .step-item {
    min-height: 0;
  }

  /* 首页标准摘要 */
  .standards-grid {
    grid-template-columns: 1fr;
    gap: 12px;
  }

  /* hero */
  .hero-section {
    padding: 32px 16px 40px;
  }

  .hero-title {
    font-size: 26px;
  }

  .hero-actions {
    flex-direction: column;
    align-items: stretch;
  }

  .btn {
    width: 100%;
  }

  /* 页面标题 */
  .page-header {
    padding: 8px 0 20px;
    margin-bottom: 24px;
  }

  .page-title {
    font-size: 24px;
  }

  /* 内容分区页 */
  .page-sections .category-grid {
    grid-template-columns: 1fr;
    gap: 12px;
  }

  .page-sections .category-card-media {
    height: 160px;
  }

  .detail-item {
    grid-template-columns: 1fr;
    gap: 12px;
    padding: 16px;
  }

  .detail-item-body {
    grid-column: 1;
  }

  /* 视频索引页 */
  .video-item {
    grid-template-columns: 100px 1fr;
    gap: 12px;
  }

  .video-thumb {
    width: 100px;
    height: 70px;
  }

  /* 专题策划页 */
  .feature-card {
    grid-template-columns: 1fr;
  }

  .feature-media {
    min-height: 0;
  }

  .feature-figure {
    min-height: 0;
    height: 180px;
  }

  .feature-figure img {
    height: 180px;
  }

  /* 观看手册页 */
  .guide-steps .step-item {
    padding-left: 20px;
  }

  .guide-media img {
    height: 180px;
  }

  /* 内容标准页 */
  .rule-table__grid {
    display: block;
    overflow-x: auto;
    white-space: nowrap;
  }

  .rule-table__grid th,
  .rule-table__grid td {
    padding: 10px 12px;
  }

  .standards-figure__img {
    height: 180px;
  }

  /* 疑问解答页 */
  .content-media-inline img {
    height: 160px;
  }

  .faq-item summary {
    padding: 14px 16px;
  }

  .faq-answer {
    padding: 12px 16px 16px;
  }

  /* 404 */
  .error-main {
    padding: 48px 16px;
  }

  .error-panel {
    padding: 32px 24px;
  }

  .error-code {
    font-size: 48px;
  }
}

/* 超小屏 */
@media (max-width: 390px) {
  .header-shell {
    padding: 8px 12px;
  }

  .section-block {
    padding: 24px 12px;
  }

  .inner-main {
    padding: 0 12px 32px;
  }

  .hero-section {
    padding: 24px 12px 32px;
  }

  .hero-media img {
    height: 200px;
  }

  .page-sections .category-card-media {
    height: 140px;
  }

  .video-item {
    grid-template-columns: 1fr;
    gap: 8px;
  }

  .video-thumb {
    width: 100%;
    height: 120px;
  }

  .video-thumb img {
    height: 120px;
  }

  .feature-figure {
    height: 160px;
  }

  .feature-figure img {
    height: 160px;
  }

  .guide-media img {
    height: 160px;
  }

  .standards-figure__img {
    height: 160px;
  }

  .content-media-inline img {
    height: 140px;
  }

  .footer-shell {
    padding: 24px 12px 20px;
  }
}

/* 程序验收反馈：移动端正文优先 */
@media (max-width: 768px) {
  .site-main :is(.page-content, .main-content, .content-main) {
    order: 1;
  }

  .site-main :is(aside, .sidebar) {
    order: 2;
  }
}