/* =========================================================
   51吃瓜视频 · 整站样式表
   农业产地风：绿色主调，黄色点缀，朴实可信
   ========================================================= */

/* =========================================================
   base — 基础变量、重置、全局字体与颜色
   ========================================================= */

:root {
  --color-primary: #2e7d32;
  --color-primary-dark: #1b5e20;
  --color-primary-light: #e8f5e9;
  --color-accent: #f9a825;
  --color-accent-light: #fff8e1;
  --color-bg: #f5f5f5;
  --color-text: #333333;
  --color-text-light: #666666;
  --color-border: #e0e0e0;
  --color-white: #ffffff;

  --container-width: 1200px;
  --container-padding: 24px;
  --radius-sm: 4px;
  --radius-md: 6px;
  --radius-lg: 8px;

  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;

  --shadow-card: 0 1px 4px rgba(0, 0, 0, 0.08);
  --shadow-hover: 0 4px 12px rgba(0, 0, 0, 0.12);

  --spacing-xs: 8px;
  --spacing-sm: 12px;
  --spacing-md: 20px;
  --spacing-lg: 32px;
  --spacing-xl: 48px;
  --spacing-xxl: 64px;
}

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

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

body {
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.6;
  color: var(--color-text);
  background-color: var(--color-bg);
  -webkit-font-smoothing: antialiased;
}

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-dark);
}

ul,
ol {
  list-style: none;
}

h1,
h2,
h3,
h4 {
  line-height: 1.3;
  font-weight: 700;
  color: var(--color-text);
}

h1 {
  font-size: 32px;
}

h2 {
  font-size: 24px;
}

h3 {
  font-size: 18px;
}

p {
  margin-bottom: 12px;
}

/* =========================================================
   layout — 全站统一骨架：页头、页脚、主容器、面包屑
   ========================================================= */

.site-header {
  background-color: var(--color-white);
  border-bottom: 2px solid var(--color-primary);
  position: sticky;
  top: 0;
  z-index: 100;
}

.header-inner {
  max-width: var(--container-width);
  margin: 0 auto;
  padding: 0 var(--container-padding);
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 72px;
}

.brand a {
  display: flex;
  flex-direction: column;
  line-height: 1.2;
}

.brand-name {
  font-size: 22px;
  font-weight: 700;
  color: var(--color-primary);
  letter-spacing: 0.5px;
}

.brand-slogan {
  font-size: 12px;
  color: var(--color-text-light);
  margin-top: 2px;
}

.site-nav {
  display: flex;
  align-items: center;
}

.nav-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
  flex-direction: column;
  gap: 5px;
}

.nav-toggle-bar {
  display: block;
  width: 24px;
  height: 2px;
  background-color: var(--color-text);
  border-radius: 2px;
}

.nav-list {
  display: flex;
  align-items: center;
  gap: 4px;
}

.nav-list li a {
  display: block;
  padding: 8px 16px;
  font-size: 15px;
  font-weight: 500;
  color: var(--color-text);
  border-radius: var(--radius-sm);
  transition: background-color 0.2s ease, color 0.2s ease;
}

.nav-list li a:hover {
  color: var(--color-primary);
  background-color: var(--color-primary-light);
}

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

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

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

.breadcrumb {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 20px 0 8px;
  font-size: 14px;
  color: var(--color-text-light);
}

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

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

.breadcrumb-sep {
  color: #999;
}

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

.page-header {
  padding: 16px 0 28px;
  border-bottom: 1px solid var(--color-border);
  margin-bottom: 32px;
}

.page-title {
  font-size: 30px;
  color: var(--color-text);
  margin-bottom: 8px;
}

.page-description {
  font-size: 16px;
  color: var(--color-text-light);
  max-width: 720px;
}

.site-footer {
  background-color: #263238;
  color: #b0bec5;
  margin-top: 64px;
}

.footer-index {
  max-width: var(--container-width);
  margin: 0 auto;
  padding: 40px var(--container-padding) 24px;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 32px;
}

.footer-group h3 {
  font-size: 16px;
  color: #eceff1;
  margin-bottom: 12px;
  font-weight: 600;
}

.footer-group ul li {
  margin-bottom: 8px;
}

.footer-group ul li a {
  color: #90a4ae;
  font-size: 14px;
}

.footer-group ul li a:hover {
  color: var(--color-accent);
}

.footer-bottom {
  border-top: 1px solid #37474f;
  padding: 16px var(--container-padding);
  text-align: center;
  font-size: 13px;
  color: #78909c;
}

.footer-bottom p {
  margin-bottom: 4px;
}

/* =========================================================
   components — 通用组件：区块标题、卡片、标签、列表
   ========================================================= */

.section-title {
  font-size: 24px;
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: 8px;
  position: relative;
  padding-left: 14px;
}

.section-title::before {
  content: "";
  position: absolute;
  left: 0;
  top: 4px;
  bottom: 4px;
  width: 4px;
  background-color: var(--color-primary);
  border-radius: 2px;
}

.section-desc {
  font-size: 15px;
  color: var(--color-text-light);
  margin-bottom: 24px;
}

.section-intro {
  font-size: 15px;
  color: var(--color-text-light);
  margin-bottom: 20px;
}

/* =========================================================
   components — 公告条
   ========================================================= */

.notice-bar {
  background-color: var(--color-accent-light);
  border-bottom: 1px solid #f0e3c0;
  padding: 8px 0;
}

.notice-bar p {
  max-width: var(--container-width);
  margin: 0 auto;
  padding: 0 var(--container-padding);
  font-size: 14px;
  color: #5d4a12;
  text-align: center;
}

/* =========================================================
   components — 首页 hero
   ========================================================= */

.hero {
  display: grid;
  grid-template-columns: 1.2fr 1fr;
  gap: 40px;
  align-items: center;
  padding: 48px 0 40px;
}

.hero-text h1 {
  font-size: 36px;
  line-height: 1.25;
  margin-bottom: 16px;
  color: var(--color-text);
}

.hero-text p {
  font-size: 16px;
  color: var(--color-text-light);
  margin-bottom: 24px;
  max-width: 520px;
}

.hero-cta {
  display: inline-block;
  background-color: var(--color-primary);
  color: var(--color-white);
  padding: 12px 28px;
  border-radius: var(--radius-md);
  font-size: 15px;
  font-weight: 600;
  transition: background-color 0.2s ease, transform 0.2s ease;
}

.hero-cta:hover {
  background-color: var(--color-primary-dark);
  color: var(--color-white);
  transform: translateY(-2px);
}

.hero-figure {
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-card);
}

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

/* =========================================================
   components — 首页频道导航带
   ========================================================= */

.channel-nav {
  padding: 32px 0;
}

.channel-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.channel-tag {
  display: inline-block;
  background-color: var(--color-white);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 10px 20px;
  font-size: 15px;
  font-weight: 500;
  color: var(--color-text);
  transition: border-color 0.2s ease, background-color 0.2s ease, color 0.2s ease;
}

.channel-tag:hover {
  border-color: var(--color-primary);
  background-color: var(--color-primary-light);
  color: var(--color-primary);
}

/* =========================================================
   components — 首页专题卡片
   ========================================================= */

.topic-cards {
  padding: 32px 0;
}

.card-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 24px;
}

.topic-card {
  background-color: var(--color-white);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-card);
  transition: box-shadow 0.2s ease, transform 0.2s ease;
}

.topic-card:hover {
  box-shadow: var(--shadow-hover);
  transform: translateY(-2px);
}

.topic-card img {
  width: 100%;
  height: 200px;
  object-fit: cover;
}

.topic-card h3 {
  padding: 16px 20px 4px;
  font-size: 19px;
}

.topic-card p {
  padding: 0 20px;
  font-size: 14px;
  color: var(--color-text-light);
  margin-bottom: 12px;
}

.topic-card a {
  display: inline-block;
  margin: 0 20px 20px;
  font-size: 14px;
  font-weight: 600;
}

/* =========================================================
   components — 首页指南步骤
   ========================================================= */

.guide-steps {
  padding: 32px 0;
}

.steps-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.step-item {
  background-color: var(--color-white);
  border-radius: var(--radius-lg);
  padding: 24px 20px;
  box-shadow: var(--shadow-card);
  border-top: 3px solid var(--color-primary);
  position: relative;
}

.step-num {
  display: inline-block;
  width: 36px;
  height: 36px;
  background-color: var(--color-accent);
  color: var(--color-white);
  font-size: 18px;
  font-weight: 700;
  border-radius: 50%;
  text-align: center;
  line-height: 36px;
  margin-bottom: 12px;
}

.step-item h3 {
  font-size: 17px;
  margin-bottom: 8px;
}

.step-item p {
  font-size: 14px;
  color: var(--color-text-light);
  margin-bottom: 12px;
}

.step-item a {
  font-size: 14px;
  font-weight: 600;
}

/* =========================================================
   components — 首页内容参考
   ========================================================= */

.content-note {
  background-color: var(--color-white);
  border-radius: var(--radius-lg);
  padding: 24px;
  margin: 32px 0;
  border-left: 4px solid var(--color-primary);
}

.content-note h2 {
  margin-bottom: 12px;
}

.content-note p {
  font-size: 14px;
  color: var(--color-text-light);
  margin-bottom: 8px;
}

.content-note a {
  font-size: 14px;
  font-weight: 600;
}

/* =========================================================
   pages — 频道分类页（channels.html）
   ========================================================= */

.layout-shell {
  display: grid;
  grid-template-columns: 1fr 300px;
  gap: 32px;
  align-items: start;
}

.channel-list-section {
  padding-bottom: 32px;
}

.channel-item {
  display: grid;
  grid-template-columns: 180px 1fr;
  gap: 20px;
  background-color: var(--color-white);
  border-radius: var(--radius-lg);
  padding: 20px;
  margin-bottom: 16px;
  box-shadow: var(--shadow-card);
  transition: box-shadow 0.2s ease;
}

.channel-item:hover {
  box-shadow: var(--shadow-hover);
}

.channel-media {
  border-radius: var(--radius-md);
  overflow: hidden;
}

.channel-media img {
  width: 100%;
  height: 120px;
  object-fit: cover;
}

.channel-body {
  display: flex;
  flex-direction: column;
  justify-content: center;
}

.channel-name {
  font-size: 18px;
  margin-bottom: 6px;
}

.channel-desc {
  font-size: 14px;
  color: var(--color-text-light);
  margin-bottom: 10px;
}

.channel-link {
  font-size: 14px;
  font-weight: 600;
}

.channel-notes {
  background-color: var(--color-primary-light);
  border-radius: var(--radius-lg);
  padding: 24px;
  margin-top: 8px;
}

.channel-notes p {
  font-size: 14px;
  color: var(--color-text);
  margin-bottom: 8px;
}

/* 侧栏 */

.sidebar {
  position: sticky;
  top: 90px;
}

.sidebar-inner {
  background-color: var(--color-white);
  border-radius: var(--radius-lg);
  padding: 20px;
  box-shadow: var(--shadow-card);
}

.sidebar-title {
  font-size: 18px;
  margin-bottom: 16px;
  padding-bottom: 10px;
  border-bottom: 2px solid var(--color-primary);
}

.sidebar-card {
  margin-bottom: 20px;
  padding-bottom: 20px;
  border-bottom: 1px solid var(--color-border);
}

.sidebar-card:last-child {
  margin-bottom: 0;
  padding-bottom: 0;
  border-bottom: none;
}

.sidebar-card img {
  width: 100%;
  height: 120px;
  object-fit: cover;
  border-radius: var(--radius-md);
  margin-bottom: 10px;
}

.sidebar-card-title {
  font-size: 16px;
  margin-bottom: 6px;
}

.sidebar-card-desc {
  font-size: 13px;
  color: var(--color-text-light);
  margin-bottom: 8px;
}

.sidebar-card-link {
  font-size: 13px;
  font-weight: 600;
}

/* =========================================================
   pages — 观看指南页（guide.html）
   ========================================================= */

.guide-section {
  margin-bottom: 40px;
}

.guide-section h2 {
  font-size: 22px;
  margin-bottom: 20px;
  padding-bottom: 10px;
  border-bottom: 2px solid var(--color-primary);
}

.guide-step {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
  align-items: center;
  background-color: var(--color-white);
  border-radius: var(--radius-lg);
  padding: 24px;
  box-shadow: var(--shadow-card);
}

.step-media {
  border-radius: var(--radius-md);
  overflow: hidden;
}

.step-media img {
  width: 100%;
  height: 220px;
  object-fit: cover;
}

.step-content p {
  font-size: 15px;
  color: var(--color-text);
  margin-bottom: 12px;
  line-height: 1.7;
}

/* FAQ 列表 */

.faq-list {
  margin-top: 8px;
}

.faq-item {
  background-color: var(--color-white);
  border-radius: var(--radius-md);
  margin-bottom: 12px;
  box-shadow: var(--shadow-card);
  overflow: hidden;
}

.faq-item summary {
  padding: 16px 20px;
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
  position: relative;
  padding-right: 40px;
  list-style: none;
}

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

.faq-item summary::after {
  content: "+";
  position: absolute;
  right: 16px;
  top: 50%;
  transform: translateY(-50%);
  font-size: 20px;
  color: var(--color-primary);
  font-weight: 400;
}

.faq-item[open] summary::after {
  content: "−";
}

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

.faq-item p {
  padding: 0 20px 16px;
  font-size: 14px;
  color: var(--color-text-light);
}

/* 相关推荐 */

.related-links {
  background-color: var(--color-white);
  border-radius: var(--radius-lg);
  padding: 20px 24px;
  margin: 32px 0;
  box-shadow: var(--shadow-card);
}

.related-links p {
  font-size: 15px;
  margin-bottom: 0;
}

.related-links a {
  font-weight: 600;
  margin: 0 8px;
}

/* =========================================================
   pages — 专题页（topic1.html）
   ========================================================= */

.topic-intro {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 32px;
  align-items: center;
  margin-bottom: 40px;
}

.topic-hero-figure {
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-card);
}

.topic-hero-figure img {
  width: 100%;
  height: 280px;
  object-fit: cover;
}

.topic-hero-figure figcaption {
  padding: 10px 16px;
  font-size: 13px;
  color: var(--color-text-light);
  background-color: var(--color-white);
}

.topic-intro-text p {
  font-size: 15px;
  color: var(--color-text);
  line-height: 1.8;
  margin-bottom: 16px;
}

.playlist-section {
  margin-bottom: 40px;
}

.playlist-section h2 {
  font-size: 22px;
  margin-bottom: 8px;
  padding-bottom: 10px;
  border-bottom: 2px solid var(--color-primary);
}

.playlist-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 16px;
  margin-top: 20px;
}

.playlist-item {
  background-color: var(--color-white);
  border-radius: var(--radius-md);
  padding: 16px 20px;
  box-shadow: var(--shadow-card);
  border-left: 3px solid var(--color-primary);
  transition: box-shadow 0.2s ease;
}

.playlist-item:hover {
  box-shadow: var(--shadow-hover);
}

.playlist-item h3 {
  font-size: 16px;
  margin-bottom: 6px;
}

.playlist-item p {
  font-size: 14px;
  color: var(--color-text-light);
  margin-bottom: 6px;
}

.playlist-item .item-note {
  font-size: 13px;
  color: var(--color-accent);
  font-weight: 600;
}

.suggestion-section {
  background-color: var(--color-primary-light);
  border-radius: var(--radius-lg);
  padding: 24px;
  margin-bottom: 32px;
}

.suggestion-section h2 {
  font-size: 20px;
  margin-bottom: 12px;
}

.suggestion-content p {
  font-size: 15px;
  color: var(--color-text);
  line-height: 1.8;
  margin-bottom: 12px;
}

/* =========================================================
   pages — 专题页（topic2.html）
   ========================================================= */

.topic-article {
  background-color: var(--color-white);
  border-radius: var(--radius-lg);
  padding: 32px;
  box-shadow: var(--shadow-card);
  margin-bottom: 32px;
}

.topic-hero-image {
  border-radius: var(--radius-lg);
  overflow: hidden;
  margin-bottom: 28px;
}

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

.topic-hero-image figcaption {
  padding: 10px 16px;
  font-size: 13px;
  color: var(--color-text-light);
  background-color: var(--color-bg);
}

.topic-article .playlist-section h2 {
  font-size: 22px;
  margin-bottom: 8px;
  padding-bottom: 10px;
  border-bottom: 2px solid var(--color-primary);
}

.topic-article .playlist-section > p {
  font-size: 14px;
  color: var(--color-text-light);
}

.topic-article .playlist-grid {
  grid-template-columns: repeat(2, 1fr);
  gap: 16px;
  margin-top: 20px;
}

.topic-article .playlist-item {
  background-color: var(--color-bg);
  border-left: 3px solid var(--color-accent);
}

.topic-article .playlist-item h3 {
  font-size: 16px;
  margin-bottom: 6px;
}

.topic-article .playlist-item p {
  font-size: 14px;
  color: var(--color-text-light);
  margin-bottom: 6px;
}

.topic-article .suggestion-section {
  background-color: var(--color-accent-light);
  border-radius: var(--radius-md);
  padding: 24px;
  margin-top: 32px;
  margin-bottom: 0;
}

.topic-article .suggestion-section h2 {
  font-size: 20px;
  margin-bottom: 12px;
  border-bottom: none;
  padding-bottom: 0;
}

.topic-article .suggestion-section p {
  font-size: 15px;
  color: var(--color-text);
  line-height: 1.8;
  margin-bottom: 12px;
}

/* =========================================================
   pages — 404 页
   ========================================================= */

.error-main {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 60vh;
}

.error-section {
  text-align: center;
  padding: 48px 24px;
  max-width: 560px;
}

.error-section h1 {
  font-size: 72px;
  color: var(--color-primary);
  margin-bottom: 16px;
  line-height: 1;
}

.error-section p {
  font-size: 16px;
  color: var(--color-text-light);
  margin-bottom: 12px;
}

.btn-back-home {
  display: inline-block;
  background-color: var(--color-primary);
  color: var(--color-white);
  padding: 12px 32px;
  border-radius: var(--radius-md);
  font-size: 15px;
  font-weight: 600;
  margin-top: 16px;
  transition: background-color 0.2s ease;
}

.btn-back-home:hover {
  background-color: var(--color-primary-dark);
  color: var(--color-white);
}

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

@media (max-width: 1024px) {
  .layout-shell {
    grid-template-columns: 1fr 260px;
    gap: 24px;
  }

  .hero {
    gap: 24px;
  }

  .hero-text h1 {
    font-size: 30px;
  }

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

@media (max-width: 768px) {
  .header-inner {
    height: 60px;
  }

  .brand-name {
    font-size: 19px;
  }

  .brand-slogan {
    font-size: 11px;
  }

  .nav-toggle {
    display: flex;
  }

  .nav-list {
    display: none;
    position: absolute;
    top: 60px;
    left: 0;
    right: 0;
    background-color: var(--color-white);
    flex-direction: column;
    align-items: stretch;
    padding: 8px 16px 16px;
    border-bottom: 2px solid var(--color-primary);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
  }

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

  .nav-list li a {
    padding: 12px 16px;
    font-size: 16px;
    border-radius: var(--radius-sm);
  }

  .nav-list li a:hover {
    background-color: var(--color-primary-light);
  }

  /* 首页 hero 改为上下布局 */
  .hero {
    grid-template-columns: 1fr;
    padding: 32px 0 24px;
    gap: 20px;
  }

  .hero-text h1 {
    font-size: 28px;
  }

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

  /* 首页卡片改单列 */
  .card-grid {
    grid-template-columns: 1fr;
  }

  .steps-grid {
    grid-template-columns: 1fr;
    gap: 16px;
  }

  /* 内页布局改单列 */
  .layout-shell {
    grid-template-columns: 1fr;
  }

  .sidebar {
    position: static;
  }

  .channel-item {
    grid-template-columns: 1fr;
  }

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

  .guide-step {
    grid-template-columns: 1fr;
    padding: 16px;
  }

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

  .topic-intro {
    grid-template-columns: 1fr;
    gap: 20px;
  }

  .topic-hero-figure img {
    height: 200px;
  }

  .playlist-grid {
    grid-template-columns: 1fr;
  }

  .topic-article {
    padding: 20px;
  }

  .topic-article .playlist-grid {
    grid-template-columns: 1fr;
  }

  .topic-hero-image img {
    height: 200px;
  }

  .page-header {
    padding: 12px 0 20px;
    margin-bottom: 24px;
  }

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

  .footer-index {
    grid-template-columns: 1fr;
    gap: 24px;
    padding: 32px var(--container-padding) 20px;
  }

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

  .header-inner {
    padding: 0 16px;
  }

  .notice-bar p {
    padding: 0 16px;
    font-size: 13px;
  }

  .section-title {
    font-size: 20px;
  }

  .error-section h1 {
    font-size: 56px;
  }
}

@media (max-width: 480px) {
  .hero-text h1 {
    font-size: 24px;
  }

  .hero-cta {
    padding: 10px 24px;
    font-size: 14px;
  }

  .channel-tag {
    padding: 8px 14px;
    font-size: 14px;
  }

  .topic-card h3 {
    font-size: 17px;
  }

  .step-item {
    padding: 20px 16px;
  }

  .content-note {
    padding: 20px 16px;
  }

  .channel-item {
    padding: 16px;
  }

  .channel-notes {
    padding: 20px 16px;
  }

  .sidebar-inner {
    padding: 16px;
  }

  .guide-section h2 {
    font-size: 20px;
  }

  .playlist-item {
    padding: 14px 16px;
  }

  .topic-article {
    padding: 16px;
  }

  .suggestion-section {
    padding: 20px 16px;
  }

  .related-links {
    padding: 16px;
  }

  .related-links a {
    display: inline-block;
    margin: 4px 8px 4px 0;
  }
}

/* =========================================================
   interaction — 轻量交互增强
   ========================================================= */

/* 滚动出现动画：仅作为增强，不影响初始可见 */
@media (prefers-reduced-motion: no-preference) {
  .topic-card,
  .step-item,
  .channel-item,
  .playlist-item {
    transition: box-shadow 0.2s ease, transform 0.2s ease;
  }

  .topic-card:hover,
  .channel-item:hover,
  .playlist-item:hover {
    transform: translateY(-2px);
  }
}

/* 焦点可见性 */
a:focus-visible,
button:focus-visible,
summary:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
}

/* 移动端触摸目标 */
@media (max-width: 768px) {
  .nav-list li a {
    min-height: 44px;
    display: flex;
    align-items: center;
  }

  .channel-tag {
    min-height: 40px;
    display: inline-flex;
    align-items: center;
  }

  .step-item a,
  .topic-card a,
  .channel-link,
  .sidebar-card-link {
    display: inline-block;
    padding: 6px 0;
    min-height: 36px;
  }
}