/* ============================================================
   base — 基础变量、全局重置与字体
   ============================================================ */
:root {
  --color-bg: #f5f5f0;
  --color-surface: #ffffff;
  --color-text: #2b2b2b;
  --color-text-secondary: #6b6b6b;
  --color-accent: #3d5a5a;
  --color-accent-light: #4a6b6b;
  --color-border: #e8e4dc;
  --color-border-dark: #d6d0c4;
  --font-body: "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-heading: "Noto Serif SC", "SimSun", serif;
  --font-mono: ui-monospace, "Courier New", monospace;
  --container-width: 1200px;
  --radius: 6px;
  --radius-sm: 4px;
  --shadow-hover: 0 4px 16px rgba(43, 43, 43, 0.08);
  --transition: 0.2s ease;
}

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

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

body {
  font-family: var(--font-body);
  font-size: 15px;
  line-height: 1.7;
  color: var(--color-text);
  background-color: var(--color-bg);
  -webkit-font-smoothing: antialiased;
}

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

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

a:hover {
  color: var(--color-accent-light);
}

ul,
ol {
  list-style: none;
}

h1,
h2,
h3,
h4 {
  font-family: var(--font-heading);
  font-weight: 600;
  line-height: 1.4;
  color: var(--color-text);
}

p {
  margin-bottom: 0;
}

/* ============================================================
   layout — 全站统一骨架：页头、页脚、主体容器
   ============================================================ */
.site-header {
  background-color: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  z-index: 100;
}

.header-inner {
  max-width: var(--container-width);
  margin: 0 auto;
  padding: 0 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 68px;
  gap: 24px;
}

.brand {
  font-family: var(--font-heading);
  font-size: 22px;
  font-weight: 700;
  letter-spacing: 0.02em;
  flex-shrink: 0;
}

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

.brand a:hover {
  color: var(--color-accent);
}

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

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

.nav-list li a {
  display: block;
  padding: 8px 16px;
  border-radius: var(--radius-sm);
  color: var(--color-text);
  font-size: 15px;
  line-height: 1.5;
  transition: background-color var(--transition), color var(--transition);
}

.nav-list li a:hover {
  background-color: rgba(61, 90, 90, 0.08);
  color: var(--color-accent);
}

.nav-list li a.is-current {
  background-color: var(--color-accent);
  color: #ffffff;
}

.nav-toggle {
  display: none;
  background: none;
  border: 1px solid var(--color-border-dark);
  border-radius: var(--radius-sm);
  width: 44px;
  height: 44px;
  padding: 10px 8px;
  cursor: pointer;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
}

.nav-toggle span {
  display: block;
  height: 2px;
  width: 100%;
  background-color: var(--color-text);
  transition: transform var(--transition), opacity var(--transition);
}

.site-main {
  min-height: 60vh;
}

.inner-main {
  max-width: var(--container-width);
  margin: 0 auto;
  padding: 32px 24px 56px;
}

.home-main {
  max-width: var(--container-width);
  margin: 0 auto;
  padding: 0 24px 56px;
}

.site-footer {
  background-color: var(--color-surface);
  border-top: 1px solid var(--color-border);
  margin-top: 56px;
}

.footer-inner {
  max-width: var(--container-width);
  margin: 0 auto;
  padding: 48px 24px 24px;
  display: grid;
  grid-template-columns: 1.4fr 1fr 1fr 1fr;
  gap: 40px;
}

.footer-col h2 {
  font-size: 16px;
  margin-bottom: 16px;
}

.footer-col p {
  font-size: 14px;
  color: var(--color-text-secondary);
  line-height: 1.8;
}

.footer-bottom {
  max-width: var(--container-width);
  margin: 0 auto;
  padding: 20px 24px 24px;
  border-top: 1px solid var(--color-border);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.footer-bottom p {
  font-size: 13px;
  color: var(--color-text-secondary);
}

/* ============================================================
   components — 通用组件：面包屑、页面标题、按钮、标签、FAQ
   ============================================================ */
.breadcrumb {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 14px;
  color: var(--color-text-secondary);
  margin-bottom: 24px;
  flex-wrap: wrap;
}

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

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

.breadcrumb-sep {
  color: var(--color-border-dark);
}

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

.page-header {
  margin-bottom: 40px;
  padding-bottom: 24px;
  border-bottom: 1px solid var(--color-border);
}

.page-title {
  font-size: 28px;
  font-weight: 700;
  margin-bottom: 12px;
}

.page-description {
  font-size: 15px;
  color: var(--color-text-secondary);
  max-width: 720px;
  line-height: 1.8;
}

.page-description a {
  color: var(--color-accent);
  text-decoration: underline;
}

.btn-primary,
.btn-secondary,
.btn-home {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 12px 28px;
  border-radius: var(--radius);
  font-size: 15px;
  font-weight: 500;
  line-height: 1.5;
  cursor: pointer;
  transition: background-color var(--transition), border-color var(--transition), box-shadow var(--transition);
  min-height: 44px;
}

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

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

.btn-secondary {
  background-color: transparent;
  color: var(--color-text);
  border: 1px solid var(--color-border-dark);
}

.btn-secondary:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
  background-color: rgba(61, 90, 90, 0.04);
}

.btn-home {
  background-color: var(--color-accent);
  color: #ffffff;
  border: 1px solid var(--color-accent);
}

.btn-home:hover {
  background-color: var(--color-accent-light);
  color: #ffffff;
}

.section-link {
  margin-top: 24px;
  font-size: 14px;
}

.section-link a {
  color: var(--color-accent);
  font-weight: 500;
}

.section-link a:hover {
  text-decoration: underline;
}

.section-desc {
  font-size: 15px;
  color: var(--color-text-secondary);
  max-width: 720px;
  margin-bottom: 24px;
  line-height: 1.8;
}

.tag {
  display: inline-block;
  padding: 2px 10px;
  border-radius: 999px;
  font-size: 12px;
  line-height: 1.6;
  font-family: var(--font-mono);
}

.tag-channel {
  background-color: rgba(61, 90, 90, 0.1);
  color: var(--color-accent);
  border: 1px solid rgba(61, 90, 90, 0.2);
}

.channel-tag {
  display: inline-block;
  padding: 6px 14px;
  border-radius: 999px;
  background-color: var(--color-surface);
  border: 1px solid var(--color-border-dark);
  font-size: 13px;
  color: var(--color-text);
  transition: border-color var(--transition), color var(--transition);
}

.channel-tag:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
}

.faq-item {
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  background-color: var(--color-surface);
  margin-bottom: 12px;
  overflow: hidden;
}

.faq-item summary {
  padding: 16px 20px;
  cursor: pointer;
  font-size: 15px;
  font-weight: 500;
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  transition: background-color var(--transition);
}

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

.faq-item summary::after {
  content: "+";
  font-size: 20px;
  font-weight: 400;
  color: var(--color-text-secondary);
  flex-shrink: 0;
  transition: transform var(--transition);
}

.faq-item[open] summary {
  background-color: rgba(61, 90, 90, 0.04);
  border-bottom: 1px solid var(--color-border);
}

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

.faq-item p {
  padding: 16px 20px;
  font-size: 14px;
  color: var(--color-text-secondary);
  line-height: 1.8;
}

/* ============================================================
   pages — 首页
   ============================================================ */
.brand-hero {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 48px;
  align-items: center;
  padding: 48px 0 40px;
  border-bottom: 1px solid var(--color-border);
}

.hero-copy h1 {
  font-size: 32px;
  font-weight: 700;
  margin-bottom: 16px;
  line-height: 1.3;
}

.slogan {
  font-size: 18px;
  color: var(--color-accent);
  font-family: var(--font-heading);
  margin-bottom: 12px;
}

.lead {
  font-size: 15px;
  color: var(--color-text-secondary);
  line-height: 1.8;
  margin-bottom: 28px;
  max-width: 480px;
}

.hero-actions {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
}

.hero-visual {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.hero-figure {
  border-radius: var(--radius);
  overflow: hidden;
  border: 1px solid var(--color-border);
  background-color: var(--color-surface);
}

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

.hero-figure figcaption {
  padding: 12px 16px;
  font-size: 13px;
  color: var(--color-text-secondary);
  border-top: 1px solid var(--color-border);
}

.channel-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.channel-overview {
  padding: 48px 0;
  border-bottom: 1px solid var(--color-border);
}

.channel-overview h2,
.topic-collections h2,
.schedule-preview h2,
.guide-steps h2,
.feedback-entry h2 {
  font-size: 22px;
  margin-bottom: 8px;
}

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

.channel-item {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 20px;
  transition: border-color var(--transition), box-shadow var(--transition);
}

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

.channel-item h3 {
  font-size: 18px;
  margin-bottom: 8px;
}

.channel-item p {
  font-size: 14px;
  color: var(--color-text-secondary);
  line-height: 1.7;
}

.topic-collections {
  padding: 48px 0;
  border-bottom: 1px solid var(--color-border);
}

.topic-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
  margin-top: 24px;
}

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

.topic-card:hover {
  border-color: var(--color-border-dark);
  box-shadow: var(--shadow-hover);
}

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

.topic-body {
  padding: 20px;
  display: flex;
  flex-direction: column;
  gap: 10px;
  flex: 1;
}

.topic-body h3 {
  font-size: 18px;
}

.topic-body p {
  font-size: 14px;
  color: var(--color-text-secondary);
  line-height: 1.7;
}

.topic-body .topic-audience {
  font-size: 13px;
  color: var(--color-text);
  background-color: rgba(61, 90, 90, 0.06);
  padding: 8px 12px;
  border-radius: var(--radius-sm);
}

.topic-body a {
  align-self: flex-start;
  margin-top: auto;
  font-size: 14px;
  font-weight: 500;
}

.schedule-preview {
  padding: 48px 0;
  border-bottom: 1px solid var(--color-border);
}

.timeline {
  margin-top: 24px;
  border-left: 2px solid var(--color-border);
  padding-left: 24px;
  display: flex;
  flex-direction: column;
  gap: 24px;
}

.timeline li {
  position: relative;
  display: flex;
  align-items: flex-start;
  gap: 16px;
}

.timeline li::before {
  content: "";
  position: absolute;
  left: -30px;
  top: 8px;
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background-color: var(--color-accent);
  border: 2px solid var(--color-surface);
}

.timeline time {
  font-family: var(--font-mono);
  font-size: 14px;
  color: var(--color-text-secondary);
  white-space: nowrap;
  min-width: 90px;
  padding-top: 2px;
}

.timeline .channel-tag {
  font-size: 12px;
  padding: 2px 10px;
  flex-shrink: 0;
}

.timeline p {
  font-size: 15px;
  color: var(--color-text);
  line-height: 1.6;
}

.guide-steps {
  padding: 48px 0;
  border-bottom: 1px solid var(--color-border);
}

.steps-list {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
  margin-top: 24px;
  counter-reset: step-counter;
}

.steps-list li {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 24px 20px;
  position: relative;
  counter-increment: step-counter;
}

.step-num {
  display: block;
  font-family: var(--font-mono);
  font-size: 13px;
  color: var(--color-accent);
  margin-bottom: 12px;
}

.step-num::before {
  content: "0" counter(step-counter);
}

.steps-list h3 {
  font-size: 18px;
  margin-bottom: 8px;
}

.steps-list p {
  font-size: 14px;
  color: var(--color-text-secondary);
  line-height: 1.7;
}

.feedback-entry {
  padding: 48px 0;
}

.faq-summary {
  margin-top: 24px;
  max-width: 720px;
}

.related-links {
  margin-top: 40px;
  padding-top: 24px;
  border-top: 1px solid var(--color-border);
  display: flex;
  align-items: center;
  gap: 16px;
  flex-wrap: wrap;
}

.related-links-label {
  font-size: 14px;
  color: var(--color-text-secondary);
}

.related-links-item {
  font-size: 14px;
  padding: 6px 14px;
  border: 1px solid var(--color-border);
  border-radius: 999px;
  color: var(--color-text);
  transition: border-color var(--transition), color var(--transition);
}

.related-links-item:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
}

/* ============================================================
   pages — 频道目录 channels.html
   ============================================================ */
.page-layout {
  display: grid;
  gap: 32px;
}

.page-layout.sidebar-left {
  grid-template-columns: 260px 1fr;
  align-items: start;
}

.sidebar-left .page-layout .channel-index {
  position: sticky;
  top: 84px;
}

.channel-index {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 24px;
}

.channel-index h2 {
  font-size: 18px;
  margin-bottom: 16px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--color-border);
}

.channel-index ul {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.channel-index a {
  display: block;
  padding: 8px 12px;
  border-radius: var(--radius-sm);
  font-size: 14px;
  color: var(--color-text);
  transition: background-color var(--transition), color var(--transition);
}

.channel-index a:hover {
  background-color: rgba(61, 90, 90, 0.08);
  color: var(--color-accent);
}

.channel-list {
  min-width: 0;
}

.channel-list .channel-group {
  display: block;
  margin-bottom: 40px;
}

.channel-list .channel-group > h2 {
  font-size: 22px;
  margin-bottom: 8px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--color-border);
}

.channel-cards {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
  margin-top: 20px;
}

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

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

.channel-card-media {
  height: 160px;
  background-color: var(--color-border);
  overflow: hidden;
}

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

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

.channel-card-body .channel-no {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--color-text-secondary);
}

.channel-card-body h3 {
  font-size: 18px;
}

.channel-desc {
  font-size: 14px;
  color: var(--color-text-secondary);
  line-height: 1.7;
}

.channel-rep {
  font-size: 13px;
  color: var(--color-text);
  background-color: rgba(61, 90, 90, 0.06);
  padding: 8px 12px;
  border-radius: var(--radius-sm);
  margin-top: auto;
}

.channel-aud {
  font-size: 13px;
  color: var(--color-text-secondary);
}

.channel-related {
  margin-top: 48px;
  padding-top: 32px;
  border-top: 1px solid var(--color-border);
}

.channel-related h2 {
  font-size: 20px;
  margin-bottom: 8px;
}

.channel-related p {
  font-size: 14px;
  color: var(--color-text-secondary);
  margin-bottom: 16px;
}

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

.channel-related a {
  display: inline-block;
  padding: 8px 16px;
  border: 1px solid var(--color-border);
  border-radius: 999px;
  font-size: 14px;
  color: var(--color-text);
  transition: border-color var(--transition), color var(--transition);
}

.channel-related a:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
}

/* ============================================================
   pages — 节目预告 schedule.html
   ============================================================ */
.schedule-timeline {
  margin-bottom: 48px;
}

.schedule-timeline h2,
.channel-update-group h2 {
  font-size: 22px;
  margin-bottom: 8px;
}

.timeline-list {
  margin-top: 24px;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.timeline-item {
  display: grid;
  grid-template-columns: 140px 1fr;
  gap: 24px;
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 20px 24px;
  transition: border-color var(--transition), box-shadow var(--transition);
}

.timeline-item:hover {
  border-color: var(--color-border-dark);
  box-shadow: var(--shadow-hover);
}

.timeline-date {
  font-family: var(--font-mono);
  font-size: 14px;
  color: var(--color-text-secondary);
  padding-top: 4px;
}

.timeline-content {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.timeline-content .tag {
  align-self: flex-start;
}

.timeline-topic {
  font-size: 16px;
  font-weight: 500;
  color: var(--color-text);
}

.timeline-note {
  font-size: 14px;
  color: var(--color-text-secondary);
  line-height: 1.7;
}

.channel-update-group {
  margin-bottom: 48px;
}

.update-cards {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
  margin-top: 24px;
}

.update-card {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 20px;
  display: flex;
  flex-direction: column;
  gap: 8px;
  transition: border-color var(--transition), box-shadow var(--transition);
}

.update-card:hover {
  border-color: var(--color-border-dark);
  box-shadow: var(--shadow-hover);
}

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

.update-card p {
  font-size: 14px;
  color: var(--color-text-secondary);
  line-height: 1.7;
  flex: 1;
}

.update-card a {
  font-size: 14px;
  font-weight: 500;
  align-self: flex-start;
}

.schedule-media {
  margin: 40px 0;
  border-radius: var(--radius);
  overflow: hidden;
  border: 1px solid var(--color-border);
  background-color: var(--color-surface);
}

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

.schedule-media figcaption {
  padding: 12px 16px;
  font-size: 13px;
  color: var(--color-text-secondary);
  border-top: 1px solid var(--color-border);
}

.related-links p {
  font-size: 14px;
  color: var(--color-text-secondary);
  margin-bottom: 12px;
}

.related-links ul {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.related-links ul a {
  display: inline-block;
  padding: 8px 16px;
  border: 1px solid var(--color-border);
  border-radius: 999px;
  font-size: 14px;
  color: var(--color-text);
  transition: border-color var(--transition), color var(--transition);
}

.related-links ul a:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
}

/* ============================================================
   pages — 往期内容 archive.html
   ============================================================ */
.archive-section {
  margin-bottom: 48px;
}

.archive-section h2 {
  font-size: 22px;
  margin-bottom: 8px;
}

.year-index-list {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  margin-top: 20px;
}

.year-index-list a {
  display: inline-block;
  padding: 10px 24px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  background-color: var(--color-surface);
  font-size: 15px;
  color: var(--color-text);
  font-family: var(--font-mono);
  transition: border-color var(--transition), color var(--transition);
}

.year-index-list a:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
}

.archive-year-group {
  margin-bottom: 40px;
}

.year-heading {
  font-size: 20px;
  margin-bottom: 20px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--color-border);
  font-family: var(--font-mono);
}

.archive-item {
  display: grid;
  grid-template-columns: 200px 1fr;
  gap: 20px;
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 16px;
  margin-bottom: 16px;
  transition: border-color var(--transition), box-shadow var(--transition);
}

.archive-item:hover {
  border-color: var(--color-border-dark);
  box-shadow: var(--shadow-hover);
}

.archive-thumb {
  border-radius: var(--radius-sm);
  overflow: hidden;
  background-color: var(--color-border);
}

.archive-thumb img {
  width: 100%;
  height: 130px;
  object-fit: cover;
}

.archive-item-body {
  display: flex;
  flex-direction: column;
  gap: 8px;
  min-width: 0;
}

.archive-meta {
  display: flex;
  gap: 16px;
  font-size: 13px;
  color: var(--color-text-secondary);
  font-family: var(--font-mono);
}

.archive-item-title {
  font-size: 17px;
  font-weight: 600;
}

.archive-summary {
  font-size: 14px;
  color: var(--color-text-secondary);
  line-height: 1.7;
}

.archive-related {
  margin-top: 40px;
  padding-top: 24px;
  border-top: 1px solid var(--color-border);
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.archive-related p {
  font-size: 14px;
  color: var(--color-text-secondary);
  margin-right: 8px;
  width: 100%;
}

.archive-related a {
  display: inline-block;
  padding: 8px 16px;
  border: 1px solid var(--color-border);
  border-radius: 999px;
  font-size: 14px;
  color: var(--color-text);
  transition: border-color var(--transition), color var(--transition);
}

.archive-related a:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
}

/* ============================================================
   pages — 观看指南 guide.html
   ============================================================ */
.guide-section {
  margin-bottom: 48px;
  padding-bottom: 40px;
  border-bottom: 1px solid var(--color-border);
}

.guide-section:last-of-type {
  border-bottom: none;
  padding-bottom: 0;
}

.section-head {
  display: flex;
  align-items: baseline;
  gap: 12px;
  margin-bottom: 12px;
}

.section-index {
  font-family: var(--font-mono);
  font-size: 14px;
  color: var(--color-accent);
}

.section-head h2 {
  font-size: 22px;
}

.section-intro {
  font-size: 15px;
  color: var(--color-text-secondary);
  line-height: 1.8;
  max-width: 720px;
  margin-bottom: 24px;
}

.steps-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
  margin-top: 24px;
}

.step-item {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 24px 20px;
  display: flex;
  flex-direction: column;
  gap: 8px;
  transition: border-color var(--transition), box-shadow var(--transition);
}

.step-item:hover {
  border-color: var(--color-border-dark);
  box-shadow: var(--shadow-hover);
}

.step-item .step-number {
  font-family: var(--font-mono);
  font-size: 13px;
  color: var(--color-accent);
}

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

.step-item p {
  font-size: 14px;
  color: var(--color-text-secondary);
  line-height: 1.7;
}

.checklist-block {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 28px;
}

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

.checklist-list li {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  font-size: 15px;
  line-height: 1.7;
}

.checklist-list li::before {
  content: "□";
  font-family: var(--font-mono);
  font-size: 16px;
  color: var(--color-accent);
  flex-shrink: 0;
  margin-top: 2px;
}

.device-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
  margin-top: 24px;
}

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

.device-item h3 {
  font-size: 17px;
}

.device-item p {
  font-size: 14px;
  color: var(--color-text-secondary);
  line-height: 1.7;
}

.guide-figure {
  margin-top: 32px;
  border-radius: var(--radius);
  overflow: hidden;
  border: 1px solid var(--color-border);
  background-color: var(--color-surface);
}

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

.guide-figure figcaption {
  padding: 12px 16px;
  font-size: 13px;
  color: var(--color-text-secondary);
  border-top: 1px solid var(--color-border);
}

/* ============================================================
   pages — 问题反馈 feedback.html
   ============================================================ */
.feedback-sidebar {
  position: sticky;
  top: 84px;
}

.sidebar-inner {
  display: flex;
  flex-direction: column;
  gap: 24px;
}

.notice-card,
.process-card {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 24px;
}

.notice-card h2,
.process-card h2 {
  font-size: 18px;
  margin-bottom: 16px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--color-border);
}

.notice-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.notice-list li {
  font-size: 14px;
  color: var(--color-text-secondary);
  line-height: 1.7;
  padding-left: 16px;
  position: relative;
}

.notice-list li::before {
  content: "•";
  position: absolute;
  left: 0;
  color: var(--color-accent);
}

.process-list {
  display: flex;
  flex-direction: column;
  gap: 16px;
  counter-reset: process-counter;
}

.process-list li {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  font-size: 14px;
  color: var(--color-text-secondary);
  line-height: 1.7;
  counter-increment: process-counter;
}

.process-list li::before {
  content: counter(process-counter);
  font-family: var(--font-mono);
  font-size: 13px;
  color: var(--color-accent);
  background-color: rgba(61, 90, 90, 0.1);
  border-radius: 50%;
  width: 24px;
  height: 24px;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  margin-top: 2px;
}

.feedback-figure {
  border-radius: var(--radius);
  overflow: hidden;
  border: 1px solid var(--color-border);
  background-color: var(--color-surface);
}

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

.feedback-figure figcaption {
  padding: 12px 16px;
  font-size: 13px;
  color: var(--color-text-secondary);
  border-top: 1px solid var(--color-border);
}

.feedback-main {
  min-width: 0;
}

.faq-section > h2 {
  font-size: 22px;
  margin-bottom: 8px;
}

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

.faq-group {
  margin-bottom: 32px;
}

.faq-group h3 {
  font-size: 18px;
  margin-bottom: 16px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--color-border);
}

.feedback-main .related-links {
  margin-top: 32px;
}

.feedback-main .related-links p {
  font-size: 14px;
  color: var(--color-text-secondary);
  margin-bottom: 12px;
}

.feedback-main .related-links a {
  display: inline-block;
  padding: 8px 16px;
  border: 1px solid var(--color-border);
  border-radius: 999px;
  font-size: 14px;
  color: var(--color-text);
  margin-right: 8px;
  margin-bottom: 8px;
  transition: border-color var(--transition), color var(--transition);
}

.feedback-main .related-links a:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
}

/* ============================================================
   pages — 404
   ============================================================ */
.error-main {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 60vh;
  padding: 48px 24px;
}

.error-section {
  text-align: center;
  max-width: 480px;
}

.error-code {
  font-family: var(--font-mono);
  font-size: 72px;
  font-weight: 700;
  color: var(--color-accent);
  line-height: 1.2;
  margin-bottom: 16px;
}

.error-section h1 {
  font-size: 24px;
  margin-bottom: 12px;
}

.error-desc {
  font-size: 15px;
  color: var(--color-text-secondary);
  margin-bottom: 28px;
  line-height: 1.8;
}

/* ============================================================
   responsive — 响应式断点
   ============================================================ */
@media (max-width: 1024px) {
  .channel-group {
    grid-template-columns: repeat(2, 1fr);
  }

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

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

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

  .footer-inner {
    grid-template-columns: 1fr 1fr;
    gap: 32px;
  }
}

@media (max-width: 900px) {
  .brand-hero {
    grid-template-columns: 1fr;
    gap: 32px;
  }

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

  .page-layout.sidebar-left {
    grid-template-columns: 1fr;
  }

  .channel-index {
    position: static;
    order: 2;
  }

  .channel-list {
    order: 1;
  }

  .sidebar-inner {
    display: grid;
    grid-template-columns: 1fr 1fr;
    align-items: start;
  }

  .feedback-figure {
    grid-column: 1 / -1;
  }

  .timeline-item {
    grid-template-columns: 110px 1fr;
    gap: 16px;
  }

  .archive-item {
    grid-template-columns: 160px 1fr;
  }
}

@media (max-width: 768px) {
  .header-inner {
    height: auto;
    min-height: 64px;
    padding: 12px 16px;
    flex-wrap: wrap;
  }

  .nav-toggle {
    display: flex;
    order: 3;
    margin-left: auto;
  }

  .site-nav {
    order: 4;
    width: 100%;
  }

  .nav-list {
    display: none;
    flex-direction: column;
    gap: 0;
    padding: 12px 0;
    border-top: 1px solid var(--color-border);
    width: 100%;
  }

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

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

  .inner-main,
  .home-main {
    padding: 24px 16px 40px;
  }

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

  .footer-bottom {
    flex-direction: column;
    text-align: center;
    padding: 16px;
  }

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

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

  .topic-card img {
    height: 180px;
  }

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

  .timeline-date {
    padding-top: 0;
  }

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

  .archive-thumb img {
    height: 180px;
  }

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

@media (max-width: 560px) {
  .channel-group {
    grid-template-columns: 1fr;
  }

  .update-cards {
    grid-template-columns: 1fr;
  }

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

  .steps-list {
    grid-template-columns: 1fr;
  }

  .sidebar-inner {
    grid-template-columns: 1fr;
  }

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

  .btn-primary,
  .btn-secondary {
    width: 100%;
  }

  .channel-tags {
    gap: 8px;
  }

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

  .brand-hero {
    padding: 32px 0;
  }

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

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

  .timeline {
    padding-left: 20px;
  }

  .timeline li {
    flex-direction: column;
    gap: 4px;
  }

  .timeline li::before {
    left: -26px;
  }

  .timeline time {
    min-width: 0;
  }
}

@media (max-width: 390px) {
  .header-inner {
    padding: 10px 12px;
  }

  .brand {
    font-size: 18px;
  }

  .nav-toggle {
    width: 40px;
    height: 40px;
  }

  .inner-main,
  .home-main {
    padding: 20px 12px 32px;
  }

  .footer-inner {
    padding: 24px 12px 12px;
  }

  .footer-bottom {
    padding: 12px;
  }

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

  .channel-card-media {
    height: 140px;
  }

  .archive-thumb img {
    height: 160px;
  }

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

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

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

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