/* ==========================================================
   Base — 基础变量、Reset 与全局字体
   ========================================================== */
:root {
  --color-primary: #2A9DF4;
  --color-primary-dark: #1b7fc9;
  --color-accent: #FF6B6B;
  --color-text: #333333;
  --color-text-light: #666666;
  --color-bg: #F5F5F5;
  --color-white: #FFFFFF;
  --color-border: #E8E8E8;
  --color-footer-bg: #2c2f33;
  --color-footer-text: #b8bcc2;
  --font-sans: Arial, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --container-width: 1200px;
  --radius: 8px;
  --radius-sm: 4px;
  --shadow: 0 2px 8px rgba(0, 0, 0, 0.06);
  --shadow-hover: 0 4px 16px rgba(0, 0, 0, 0.1);
  --transition: 0.25s ease;
}

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
}

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;
  -moz-osx-font-smoothing: grayscale;
}

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

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

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

ul,
ol {
  list-style: none;
}

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

h1 {
  font-size: 28px;
  font-weight: 700;
}

h2 {
  font-size: 22px;
  font-weight: 700;
}

h3 {
  font-size: 18px;
  font-weight: 600;
}

h4 {
  font-size: 16px;
  font-weight: 600;
}

p {
  margin-bottom: 0.8em;
}

/* ==========================================================
   Layout — 页面骨架、容器、页头、页脚
   ========================================================== */

/* 全站统一容器宽度 */
.header-shell,
.footer-shell,
.hero-section,
.channel-strip,
.updates-preview,
.topics-grid,
.guide-entry,
.feedback-note,
.inner-main,
.error-content {
  width: 100%;
  max-width: var(--container-width);
  margin-left: auto;
  margin-right: auto;
  padding-left: 24px;
  padding-right: 24px;
}

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

.header-shell {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}

.brand-logo {
  display: flex;
  align-items: center;
  flex-shrink: 0;
}

.brand-name {
  font-size: 22px;
  font-weight: 700;
  color: var(--color-text);
  letter-spacing: 0.02em;
}

.brand-name::before {
  content: "";
  display: inline-block;
  width: 8px;
  height: 8px;
  background-color: var(--color-accent);
  border-radius: 50%;
  margin-right: 8px;
  vertical-align: 2px;
}

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

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

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

.nav-list li a:hover {
  color: var(--color-primary);
  background-color: rgba(42, 157, 244, 0.08);
}

.nav-list li a.is-current {
  color: var(--color-primary);
  font-weight: 600;
  background-color: rgba(42, 157, 244, 0.1);
}

/* 汉堡按钮 — 默认隐藏 */
.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 44px;
  height: 44px;
  padding: 10px;
  background: none;
  border: none;
  cursor: pointer;
}

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

/* 面包屑 */
.breadcrumb {
  width: 100%;
  max-width: var(--container-width);
  margin: 0 auto;
  padding: 16px 24px 0;
  font-size: 14px;
  color: var(--color-text-light);
}

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

.breadcrumb a:hover {
  text-decoration: underline;
}

.breadcrumb-sep {
  margin: 0 8px;
  color: #aaa;
}

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

/* 面包屑（topics 页 ol 形式） */
.breadcrumb ol {
  display: flex;
  align-items: center;
  gap: 8px;
  list-style: none;
  padding: 0;
}

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

.breadcrumb ol li:last-child {
  color: var(--color-text-light);
  font-weight: 500;
}

.breadcrumb ol li + li::before {
  content: "›";
  margin-right: 8px;
  color: #aaa;
}

/* 主内容区 */
.site-main {
  min-height: 60vh;
}

.inner-main {
  padding-top: 24px;
  padding-bottom: 64px;
}

/* 内页标题区 */
.page-header {
  margin-bottom: 32px;
  padding-top: 8px;
}

.page-title {
  font-size: 28px;
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: 8px;
}

.page-description {
  font-size: 16px;
  color: var(--color-text-light);
  max-width: 720px;
  line-height: 1.7;
}

/* 页脚 */
.site-footer {
  background-color: var(--color-footer-bg);
  color: var(--color-footer-text);
  padding-top: 48px;
  margin-top: 0;
}

.footer-shell {
  padding-bottom: 24px;
}

.footer-brand p {
  font-size: 14px;
  color: var(--color-footer-text);
  line-height: 1.7;
  margin-bottom: 24px;
  max-width: 480px;
}

.footer-links {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 32px;
  margin-bottom: 32px;
}

.footer-group h4 {
  font-size: 15px;
  color: var(--color-white);
  margin-bottom: 12px;
  font-weight: 600;
}

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

.footer-group ul li a {
  font-size: 14px;
  color: var(--color-footer-text);
  transition: color var(--transition);
}

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

.footer-bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 20px;
  border-top: 1px solid rgba(255, 255, 255, 0.1);
}

.footer-bottom p {
  font-size: 13px;
  color: #888;
  margin-bottom: 0;
}

.back-to-top {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background-color: rgba(255, 255, 255, 0.08);
  color: var(--color-footer-text);
  font-size: 20px;
  transition: background-color var(--transition), color var(--transition);
}

.back-to-top:hover {
  background-color: var(--color-primary);
  color: var(--color-white);
}

.back-to-top::before {
  content: "↑";
  font-size: 18px;
  line-height: 1;
}

/* ==========================================================
   Components — 通用组件
   ========================================================== */

/* 区块标题 */
.section-title {
  font-size: 22px;
  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-intro {
  font-size: 15px;
  color: var(--color-text-light);
  margin-bottom: 24px;
  max-width: 720px;
}

/* 主按钮 */
.btn-primary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 10px 28px;
  background-color: var(--color-primary);
  color: var(--color-white);
  font-size: 15px;
  font-weight: 600;
  border-radius: var(--radius);
  transition: background-color var(--transition), transform var(--transition);
}

.btn-primary:hover {
  background-color: var(--color-primary-dark);
  color: var(--color-white);
  transform: translateY(-1px);
}

/* 次按钮 */
.btn-secondary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 10px 28px;
  background-color: var(--color-white);
  color: var(--color-primary);
  font-size: 15px;
  font-weight: 600;
  border: 1px solid var(--color-primary);
  border-radius: var(--radius);
  transition: background-color var(--transition), color var(--transition);
}

.btn-secondary:hover {
  background-color: rgba(42, 157, 244, 0.08);
  color: var(--color-primary-dark);
}

/* 文字链接 */
.text-link {
  font-size: 14px;
  font-weight: 600;
  color: var(--color-primary);
  display: inline-flex;
  align-items: center;
  gap: 4px;
}

.text-link::after {
  content: "→";
  transition: transform var(--transition);
}

.text-link:hover::after {
  transform: translateX(3px);
}

/* 更多链接 */
.more-link {
  display: inline-block;
  font-size: 14px;
  font-weight: 600;
  color: var(--color-primary);
  margin-top: 16px;
}

.more-link:hover {
  color: var(--color-primary-dark);
  text-decoration: underline;
}

/* 内容图片 */
.content-media {
  margin-bottom: 24px;
}

.content-media img {
  width: 100%;
  height: auto;
  border-radius: var(--radius);
}

.content-media-inline {
  max-width: 640px;
}

.content-media-inline figcaption {
  font-size: 13px;
  color: var(--color-text-light);
  text-align: center;
  margin-top: 8px;
  line-height: 1.5;
}

/* ==========================================================
   Pages — 首页
   ========================================================== */

/* 首屏 hero */
.hero-section {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 48px;
  align-items: center;
  padding-top: 56px;
  padding-bottom: 56px;
}

.hero-copy {
  padding-right: 24px;
}

.hero-copy h1 {
  font-size: 32px;
  font-weight: 700;
  line-height: 1.3;
  margin-bottom: 12px;
  color: var(--color-text);
}

.hero-tagline {
  font-size: 18px;
  font-weight: 500;
  color: var(--color-primary);
  margin-bottom: 12px;
}

.hero-description {
  font-size: 16px;
  color: var(--color-text-light);
  line-height: 1.7;
  margin-bottom: 24px;
  max-width: 540px;
}

.hero-media {
  position: relative;
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow);
}

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

/* 频道分类导航带 */
.channel-strip {
  padding-top: 40px;
  padding-bottom: 40px;
}

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

.channel-tags li a {
  display: inline-block;
  padding: 8px 20px;
  background-color: var(--color-white);
  border: 1px solid var(--color-border);
  border-radius: 24px;
  font-size: 14px;
  color: var(--color-text);
  transition: border-color var(--transition), color var(--transition), background-color var(--transition);
}

.channel-tags li a:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
  background-color: rgba(42, 157, 244, 0.04);
}

/* 最新动态列表 */
.updates-preview {
  padding-top: 40px;
  padding-bottom: 40px;
}

.updates-list {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.update-item {
  background-color: var(--color-white);
  border-radius: var(--radius);
  padding: 20px 24px;
  border: 1px solid var(--color-border);
  transition: box-shadow var(--transition);
}

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

.update-item article {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.update-item h3 {
  font-size: 17px;
  font-weight: 600;
}

.update-item h3 a {
  color: var(--color-text);
}

.update-item h3 a:hover {
  color: var(--color-primary);
}

.update-date {
  font-size: 13px;
  color: var(--color-text-light);
  margin-bottom: 4px;
}

.update-item p:last-child {
  font-size: 15px;
  color: var(--color-text-light);
  margin-bottom: 0;
  line-height: 1.6;
}

/* 专题推荐区 */
.topics-grid {
  padding-top: 40px;
  padding-bottom: 40px;
}

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

.topic-card {
  background-color: var(--color-white);
  border-radius: var(--radius);
  overflow: hidden;
  border: 1px solid var(--color-border);
  transition: box-shadow var(--transition), transform var(--transition);
}

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

.topic-card img {
  width: 100%;
  height: 180px;
  object-fit: cover;
}

.topic-card h3 {
  padding: 16px 20px 4px;
  font-size: 17px;
  font-weight: 600;
}

.topic-card h3 a {
  color: var(--color-text);
}

.topic-card h3 a:hover {
  color: var(--color-primary);
}

.topic-card p {
  padding: 0 20px 20px;
  font-size: 14px;
  color: var(--color-text-light);
  line-height: 1.6;
  margin-bottom: 0;
}

/* 观看指南入口 */
.guide-entry {
  padding-top: 40px;
  padding-bottom: 40px;
}

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

.guide-card {
  background-color: var(--color-white);
  border-radius: var(--radius);
  padding: 28px;
  border: 1px solid var(--color-border);
  display: flex;
  flex-direction: column;
  gap: 8px;
  transition: box-shadow var(--transition);
}

.guide-card:hover {
  box-shadow: var(--shadow-hover);
}

.guide-card h3 {
  font-size: 18px;
  font-weight: 600;
}

.guide-card h3 a {
  color: var(--color-text);
}

.guide-card h3 a:hover {
  color: var(--color-primary);
}

.guide-card p {
  font-size: 14px;
  color: var(--color-text-light);
  line-height: 1.6;
  margin-bottom: 8px;
  flex-grow: 1;
}

/* 问题反馈说明 */
.feedback-note {
  padding-top: 40px;
  padding-bottom: 56px;
}

.feedback-note p {
  font-size: 15px;
  color: var(--color-text-light);
  line-height: 1.7;
  max-width: 720px;
}

.feedback-note p a {
  color: var(--color-primary);
  font-weight: 500;
}

.feedback-note p a:hover {
  text-decoration: underline;
}

/* ==========================================================
   Pages — 频道分类页
   ========================================================== */

.channels-content {
  display: flex;
  flex-direction: column;
  gap: 48px;
}

.channel-list-section h2,
.channel-guide-section h2,
.channel-guide-entry h2 {
  margin-bottom: 8px;
}

.channel-list-section > p,
.channel-guide-section > p {
  font-size: 15px;
  color: var(--color-text-light);
  margin-bottom: 24px;
  max-width: 720px;
}

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

.channel-card {
  background-color: var(--color-white);
  border-radius: var(--radius);
  overflow: hidden;
  border: 1px solid var(--color-border);
  display: flex;
  flex-direction: column;
  transition: box-shadow var(--transition);
}

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

.channel-figure {
  overflow: hidden;
}

.channel-figure img {
  width: 100%;
  height: 200px;
  object-fit: cover;
  transition: transform 0.4s ease;
}

.channel-card:hover .channel-figure img {
  transform: scale(1.03);
}

.channel-info {
  padding: 20px;
  display: flex;
  flex-direction: column;
  gap: 8px;
  flex-grow: 1;
}

.channel-info h3 {
  font-size: 17px;
  font-weight: 600;
}

.channel-info p {
  font-size: 14px;
  color: var(--color-text-light);
  line-height: 1.6;
  margin-bottom: 8px;
  flex-grow: 1;
}

.channel-info a {
  font-size: 14px;
  font-weight: 600;
  color: var(--color-primary);
  align-self: flex-start;
}

.channel-info a:hover {
  text-decoration: underline;
}

/* 频道页观看指南区块 */
.guide-note-list {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
  margin-top: 24px;
}

.guide-note {
  background-color: var(--color-white);
  border-radius: var(--radius);
  padding: 24px;
  border: 1px solid var(--color-border);
}

.guide-note h3 {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 8px;
  color: var(--color-primary);
}

.guide-note p {
  font-size: 14px;
  color: var(--color-text-light);
  line-height: 1.6;
  margin-bottom: 0;
}

/* 频道页指南入口 */
.channel-guide-entry {
  background-color: var(--color-white);
  border-radius: var(--radius);
  padding: 32px;
  border: 1px solid var(--color-border);
}

.channel-guide-entry h2 {
  margin-bottom: 8px;
}

.channel-guide-entry p {
  font-size: 15px;
  color: var(--color-text-light);
  line-height: 1.7;
  max-width: 720px;
}

.channel-guide-entry p a {
  color: var(--color-primary);
  font-weight: 500;
}

.channel-guide-entry p a:hover {
  text-decoration: underline;
}

/* ==========================================================
   Pages — 内容专题页
   ========================================================== */

.topics-section {
  margin-bottom: 48px;
}

.topics-section h2,
.topics-summary h2 {
  margin-bottom: 8px;
}

.topics-section > p,
.topics-summary > p {
  font-size: 15px;
  color: var(--color-text-light);
  margin-bottom: 24px;
  max-width: 720px;
}

.topics-grid {
  padding: 0;
  margin-bottom: 24px;
}

.topic-card {
  display: flex;
  flex-direction: column;
}

.topic-media {
  overflow: hidden;
}

.topic-media img {
  width: 100%;
  height: 180px;
  object-fit: cover;
  transition: transform 0.4s ease;
}

.topic-card:hover .topic-media img {
  transform: scale(1.03);
}

.topic-content {
  padding: 20px;
  display: flex;
  flex-direction: column;
  gap: 8px;
  flex-grow: 1;
}

.topic-content h3 {
  font-size: 17px;
  font-weight: 600;
}

.topic-content h3 a {
  color: var(--color-text);
}

.topic-content h3 a:hover {
  color: var(--color-primary);
}

.topic-content p {
  font-size: 14px;
  color: var(--color-text-light);
  line-height: 1.6;
  margin-bottom: 8px;
  flex-grow: 1;
}

.topic-content a {
  font-size: 14px;
  font-weight: 600;
  color: var(--color-primary);
  align-self: flex-start;
}

.topic-content a:hover {
  text-decoration: underline;
}

/* 专题摘要 */
.summary-list {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 24px;
  margin-bottom: 24px;
}

.summary-item {
  background-color: var(--color-white);
  border-radius: var(--radius);
  padding: 24px;
  border: 1px solid var(--color-border);
}

.summary-item h3 {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 8px;
}

.summary-item p {
  font-size: 14px;
  color: var(--color-text-light);
  line-height: 1.6;
  margin-bottom: 0;
}

.summary-note {
  font-size: 14px;
  color: var(--color-text-light);
}

.summary-note a {
  color: var(--color-primary);
  font-weight: 500;
}

.summary-note a:hover {
  text-decoration: underline;
}

/* ==========================================================
   Pages — 观看指南页
   ========================================================== */

.guide-section {
  margin-bottom: 48px;
}

.guide-section .section-title {
  margin-bottom: 16px;
}

.guide-section .content-media {
  margin-bottom: 16px;
}

.guide-section .section-intro {
  margin-bottom: 24px;
}

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

.step-card {
  background-color: var(--color-white);
  border-radius: var(--radius);
  padding: 24px;
  border: 1px solid var(--color-border);
  position: relative;
  transition: box-shadow var(--transition);
}

.step-card:hover {
  box-shadow: var(--shadow-hover);
}

.step-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  background-color: var(--color-primary);
  color: var(--color-white);
  font-size: 15px;
  font-weight: 700;
  border-radius: 50%;
  margin-bottom: 12px;
}

.step-card h3 {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 8px;
}

.step-card p {
  font-size: 14px;
  color: var(--color-text-light);
  line-height: 1.6;
  margin-bottom: 0;
}

/* 入口核验方法 */
.method-list {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
  margin-bottom: 24px;
}

.method-item {
  background-color: var(--color-white);
  border-radius: var(--radius);
  padding: 20px;
  border: 1px solid var(--color-border);
}

.method-item h3 {
  font-size: 15px;
  font-weight: 600;
  margin-bottom: 6px;
  color: var(--color-primary);
}

.method-item p {
  font-size: 14px;
  color: var(--color-text-light);
  line-height: 1.6;
  margin-bottom: 0;
}

/* 注意事项 */
.notice-list {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

.notice-list .method-item {
  border-left: 3px solid var(--color-accent);
}

/* 相关链接 */
.guide-related {
  margin-top: 40px;
}

.guide-related .section-title {
  margin-bottom: 20px;
}

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

.related-card {
  background-color: var(--color-white);
  border-radius: var(--radius);
  padding: 20px;
  border: 1px solid var(--color-border);
  display: flex;
  flex-direction: column;
  gap: 4px;
  transition: box-shadow var(--transition), border-color var(--transition);
}

.related-card:hover {
  box-shadow: var(--shadow-hover);
  border-color: var(--color-primary);
}

.related-name {
  font-size: 16px;
  font-weight: 600;
  color: var(--color-text);
}

.related-card:hover .related-name {
  color: var(--color-primary);
}

.related-desc {
  font-size: 13px;
  color: var(--color-text-light);
  line-height: 1.5;
}

/* ==========================================================
   Pages — 更新动态页
   ========================================================== */

.updates-layout {
  display: flex;
  flex-direction: column;
  gap: 48px;
}

.updates-section h2 {
  margin-bottom: 8px;
}

.updates-section .section-intro {
  margin-bottom: 24px;
}

.updates-timeline {
  display: flex;
  flex-direction: column;
  gap: 0;
  position: relative;
}

.updates-timeline::before {
  content: "";
  position: absolute;
  left: 55px;
  top: 8px;
  bottom: 8px;
  width: 2px;
  background-color: var(--color-border);
}

.update-item {
  display: flex;
  gap: 24px;
  align-items: flex-start;
  position: relative;
  background: none;
  border: none;
  padding: 16px 0;
}

.update-item:hover {
  box-shadow: none;
}

.update-date {
  flex-shrink: 0;
  width: 56px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  background-color: var(--color-white);
  border-radius: var(--radius);
  border: 1px solid var(--color-border);
  padding: 8px 4px;
  z-index: 1;
}

.date-day {
  font-size: 20px;
  font-weight: 700;
  color: var(--color-primary);
  line-height: 1.2;
}

.date-month {
  font-size: 12px;
  color: var(--color-text-light);
  line-height: 1.2;
}

.update-content {
  background-color: var(--color-white);
  border-radius: var(--radius);
  padding: 20px 24px;
  border: 1px solid var(--color-border);
  flex-grow: 1;
  transition: box-shadow var(--transition);
}

.update-content:hover {
  box-shadow: var(--shadow-hover);
}

.update-content h3 {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 6px;
}

.update-content h3 a {
  color: var(--color-text);
}

.update-content h3 a:hover {
  color: var(--color-primary);
}

.update-content p {
  font-size: 14px;
  color: var(--color-text-light);
  line-height: 1.6;
  margin-bottom: 0;
}

/* 更新说明区块 */
.updates-note {
  display: grid;
  grid-template-columns: 0.9fr 1.1fr;
  gap: 32px;
  align-items: center;
  background-color: var(--color-white);
  border-radius: var(--radius);
  padding: 32px;
  border: 1px solid var(--color-border);
}

.updates-figure {
  overflow: hidden;
  border-radius: var(--radius);
}

.updates-image {
  width: 100%;
  height: 240px;
  object-fit: cover;
}

.updates-figure figcaption {
  font-size: 13px;
  color: var(--color-text-light);
  text-align: center;
  margin-top: 8px;
}

.note-content h2 {
  font-size: 20px;
  font-weight: 700;
  margin-bottom: 12px;
}

.note-content p {
  font-size: 14px;
  color: var(--color-text-light);
  line-height: 1.7;
  margin-bottom: 12px;
}

.note-content p:last-child {
  margin-bottom: 0;
}

/* ==========================================================
   Pages — 常见问题页
   ========================================================== */

.page-shell {
  display: flex;
  flex-direction: column;
  gap: 48px;
}

.faq-section .section-title,
.faq-solution .section-title,
.faq-contact .section-title {
  margin-bottom: 16px;
}

.faq-section .content-media {
  margin-bottom: 24px;
}

.faq-accordion {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.faq-item {
  background-color: var(--color-white);
  border-radius: var(--radius);
  border: 1px solid var(--color-border);
  overflow: hidden;
  transition: box-shadow var(--transition);
}

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

.faq-item summary {
  padding: 18px 24px;
  font-size: 16px;
  font-weight: 600;
  color: var(--color-text);
  cursor: pointer;
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  transition: color var(--transition);
}

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

.faq-item summary::after {
  content: "+";
  font-size: 22px;
  font-weight: 400;
  color: var(--color-primary);
  flex-shrink: 0;
  transition: transform var(--transition);
}

.faq-item[open] summary {
  color: var(--color-primary);
}

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

.faq-answer {
  padding: 0 24px 20px;
  font-size: 14px;
  color: var(--color-text-light);
  line-height: 1.7;
}

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

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

/* 解决方案 */
.solution-steps {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.solution-card {
  background-color: var(--color-white);
  border-radius: var(--radius);
  padding: 24px;
  border: 1px solid var(--color-border);
}

.solution-card h3 {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 12px;
  color: var(--color-primary);
}

.solution-card ol {
  list-style: decimal;
  padding-left: 20px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.solution-card ol li {
  font-size: 14px;
  color: var(--color-text-light);
  line-height: 1.6;
}

/* 联系反馈 */
.contact-note {
  background-color: var(--color-white);
  border-radius: var(--radius);
  padding: 28px;
  border: 1px solid var(--color-border);
}

.contact-note p {
  font-size: 15px;
  color: var(--color-text-light);
  line-height: 1.7;
  max-width: 720px;
  margin-bottom: 8px;
}

.contact-note p:last-child {
  margin-bottom: 0;
}

.contact-note p a {
  color: var(--color-primary);
  font-weight: 500;
}

.contact-note p a:hover {
  text-decoration: underline;
}

/* ==========================================================
   Pages — 404 页
   ========================================================== */

.error-main {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 70vh;
  padding: 48px 24px;
}

.error-content {
  text-align: center;
  max-width: 560px;
}

.error-code {
  font-size: 72px;
  font-weight: 700;
  color: var(--color-primary);
  line-height: 1.2;
  margin-bottom: 8px;
}

.error-content h1 {
  font-size: 26px;
  margin-bottom: 12px;
}

.error-desc {
  font-size: 16px;
  color: var(--color-text-light);
  line-height: 1.7;
  margin-bottom: 24px;
}

.error-actions {
  display: flex;
  gap: 16px;
  justify-content: center;
  margin-bottom: 24px;
}

.error-help {
  font-size: 14px;
  color: var(--color-text-light);
}

.error-help a {
  color: var(--color-primary);
  font-weight: 500;
}

.error-help a:hover {
  text-decoration: underline;
}

/* ==========================================================
   Responsive — 响应式
   ========================================================== */

@media (max-width: 1024px) {
  .channel-strip,
  .updates-preview,
  .topics-grid,
  .guide-entry,
  .feedback-note,
  .inner-main,
  .hero-section {
    padding-left: 20px;
    padding-right: 20px;
  }

  .guide-note-list {
    grid-template-columns: repeat(2, 1fr);
  }

  .method-list,
  .notice-list {
    grid-template-columns: repeat(2, 1fr);
  }

  .related-links {
    grid-template-columns: repeat(2, 1fr);
  }

  .solution-steps {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 768px) {
  /* 页头 */
  .header-shell {
    height: 56px;
  }

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

  /* 汉堡菜单 */
  .nav-toggle {
    display: flex;
  }

  .site-nav {
    position: absolute;
    top: 56px;
    left: 0;
    right: 0;
    background-color: var(--color-white);
    border-bottom: 1px solid var(--color-border);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.06);
    display: block;
  }

  .nav-list {
    display: none;
    flex-direction: column;
    align-items: stretch;
    padding: 8px 16px 16px;
  }

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

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

  /* 面包屑 */
  .breadcrumb {
    padding: 12px 20px 0;
  }

  /* 内页 */
  .inner-main {
    padding-top: 16px;
    padding-bottom: 40px;
  }

  .page-header {
    margin-bottom: 24px;
  }

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

  /* 首页 hero */
  .hero-section {
    grid-template-columns: 1fr;
    gap: 24px;
    padding-top: 32px;
    padding-bottom: 32px;
  }

  .hero-copy {
    padding-right: 0;
  }

  .hero-copy h1 {
    font-size: 26px;
  }

  .hero-media img {
    height: 220px;
  }

  /* 首页模块间距 */
  .channel-strip,
  .updates-preview,
  .topics-grid,
  .guide-entry,
  .feedback-note {
    padding-top: 28px;
    padding-bottom: 28px;
  }

  /* 卡片网格 */
  .topic-cards,
  .guide-cards,
  .channel-grid,
  .summary-list,
  .steps-wrap {
    grid-template-columns: 1fr;
  }

  /* 更新动态 */
  .updates-timeline::before {
    left: 24px;
  }

  .update-item {
    gap: 16px;
  }

  .update-date {
    width: 48px;
    padding: 6px 2px;
  }

  .date-day {
    font-size: 17px;
  }

  .updates-note {
    grid-template-columns: 1fr;
    padding: 20px;
  }

  .updates-image {
    height: 180px;
  }

  /* 频道页 */
  .guide-note-list,
  .method-list,
  .notice-list,
  .related-links,
  .solution-steps {
    grid-template-columns: 1fr;
  }

  /* 页脚 */
  .site-footer {
    padding-top: 32px;
  }

  .footer-links {
    grid-template-columns: 1fr;
    gap: 24px;
  }

  .footer-bottom {
    flex-direction: column;
    gap: 12px;
    text-align: center;
  }

  /* 404 */
  .error-code {
    font-size: 56px;
  }

  .error-actions {
    flex-direction: column;
    align-items: center;
  }
}

@media (max-width: 480px) {
  .header-shell,
  .breadcrumb,
  .inner-main,
  .hero-section,
  .channel-strip,
  .updates-preview,
  .topics-grid,
  .guide-entry,
  .feedback-note,
  .footer-shell {
    padding-left: 16px;
    padding-right: 16px;
  }

  .hero-description {
    font-size: 15px;
  }

  .channel-tags {
    gap: 8px;
  }

  .channel-tags li a {
    padding: 6px 14px;
    font-size: 13px;
  }

  .update-item {
    flex-direction: column;
    gap: 8px;
  }

  .updates-timeline::before {
    display: none;
  }

  .update-date {
    flex-direction: row;
    width: auto;
    gap: 6px;
    padding: 4px 12px;
  }

  .update-content {
    padding: 16px;
  }

  .topic-card img,
  .topic-media img {
    height: 160px;
  }

  .guide-card {
    padding: 20px;
  }

  .channel-info {
    padding: 16px;
  }

  .channel-figure img {
    height: 170px;
  }

  .step-card,
  .summary-item,
  .solution-card,
  .guide-note {
    padding: 16px;
  }

  .faq-item summary {
    padding: 14px 16px;
    font-size: 15px;
  }

  .faq-answer {
    padding: 0 16px 16px;
    font-size: 14px;
  }

  .contact-note {
    padding: 20px;
  }
}

/* ==========================================================
   Interaction — 交互增强（不影响初始可见性）
   ========================================================== */

/* 滚动出现动画 — 仅增强，不隐藏初始内容 */
@media (prefers-reduced-motion: no-preference) {
  .topic-card,
  .guide-card,
  .channel-card,
  .step-card,
  .summary-item,
  .solution-card {
    transition: box-shadow var(--transition), transform var(--transition);
  }

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

/* 图片对话框放大 */
.lightbox-open {
  overflow: hidden;
}

.lightbox-overlay {
  position: fixed;
  inset: 0;
  background-color: rgba(0, 0, 0, 0.85);
  z-index: 9999;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: zoom-out;
}

.lightbox-overlay img {
  max-width: 90vw;
  max-height: 90vh;
  object-fit: contain;
  border-radius: 4px;
}

.lightbox-close {
  position: absolute;
  top: 16px;
  right: 24px;
  width: 44px;
  height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(255, 255, 255, 0.15);
  color: #fff;
  font-size: 28px;
  border: none;
  border-radius: 50%;
  cursor: pointer;
  transition: background-color var(--transition);
}

.lightbox-close:hover {
  background-color: rgba(255, 255, 255, 0.3);
}