/* ==========================================================================
   51吃瓜台北娜娜 · 整站样式表
   学术期刊风：衬线正文、摘要区、脚注编号、克制图表颜色
   ========================================================================== */

/* ==========================================================================
   Base
   ========================================================================== */

:root {
  --color-primary: #2C3E50;
  --color-accent: #E74C3C;
  --color-bg: #ECF0F1;
  --color-bg-light: #F5F5F5;
  --color-text: #34495E;
  --color-white: #ffffff;
  --color-border: #d8dee3;
  --font-serif: Georgia, "Times New Roman", "Songti SC", "SimSun", serif;
  --font-sans: Helvetica, "PingFang SC", "Microsoft YaHei", Arial, sans-serif;
  --container-width: 1200px;
  --content-width: 860px;
  --radius: 8px;
  --transition: 0.2s ease;
}

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

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

body {
  font-family: var(--font-serif);
  font-size: 1rem;
  line-height: 1.75;
  color: var(--color-text);
  background-color: var(--color-bg-light);
  -webkit-font-smoothing: antialiased;
}

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

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

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

ul,
ol {
  list-style: none;
}

h1,
h2,
h3,
h4 {
  font-family: var(--font-sans);
  line-height: 1.3;
  color: var(--color-primary);
}

h1 {
  font-size: 2rem;
  font-weight: 700;
}

h2 {
  font-size: 1.5rem;
  font-weight: 600;
}

h3 {
  font-size: 1.125rem;
  font-weight: 600;
}

p {
  margin-bottom: 1rem;
}

/* ==========================================================================
   Layout
   ========================================================================== */

.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;
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 64px;
  gap: 24px;
}

.brand-name {
  font-family: var(--font-sans);
  font-size: 1.25rem;
  font-weight: 700;
  margin: 0;
  white-space: nowrap;
}

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

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

.site-main {
  max-width: var(--container-width);
  margin: 0 auto;
  padding: 32px 24px 48px;
}

.inner-main {
  max-width: var(--container-width);
  margin: 0 auto;
  padding: 32px 24px 48px;
}

.site-footer {
  background-color: var(--color-primary);
  color: var(--color-bg);
  margin-top: 48px;
}

.footer-shell {
  max-width: var(--container-width);
  margin: 0 auto;
  padding: 48px 24px 24px;
}

.footer-brand {
  margin-bottom: 32px;
}

.footer-slogan {
  font-family: var(--font-sans);
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--color-white);
  margin-bottom: 8px;
}

.footer-desc {
  font-size: 0.9rem;
  color: var(--color-bg);
  max-width: 560px;
  line-height: 1.6;
}

.footer-links {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 32px;
  margin-bottom: 32px;
}

.footer-heading {
  font-size: 0.95rem;
  color: var(--color-white);
  margin-bottom: 12px;
  font-weight: 600;
}

.footer-links .link-group ul li {
  margin-bottom: 6px;
}

.footer-links .link-group ul li a {
  color: var(--color-bg);
  font-size: 0.9rem;
  font-family: var(--font-sans);
}

.footer-links .link-group ul li a:hover {
  color: var(--color-white);
  text-decoration: underline;
}

.copyright {
  border-top: 1px solid rgba(255, 255, 255, 0.15);
  padding-top: 16px;
  font-size: 0.85rem;
  color: var(--color-bg);
  font-family: var(--font-sans);
}

/* ==========================================================================
   导航
   ========================================================================== */

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

.site-nav .nav-list li a {
  display: block;
  padding: 8px 14px;
  font-family: var(--font-sans);
  font-size: 0.9rem;
  color: var(--color-text);
  border-radius: 4px;
}

.site-nav .nav-list li a:hover {
  color: var(--color-accent);
  background-color: var(--color-bg);
}

.site-nav .nav-list li a.is-current {
  color: var(--color-accent);
  font-weight: 600;
  background-color: rgba(231, 76, 60, 0.08);
}

.nav-toggle {
  display: none;
  background: none;
  border: 1px solid var(--color-border);
  border-radius: 4px;
  width: 44px;
  height: 44px;
  cursor: pointer;
  position: relative;
}

.nav-toggle::before,
.nav-toggle::after {
  content: "";
  position: absolute;
  left: 12px;
  right: 12px;
  height: 2px;
  background-color: var(--color-primary);
}

.nav-toggle::before {
  top: 16px;
}

.nav-toggle::after {
  bottom: 16px;
}

/* ==========================================================================
   面包屑
   ========================================================================== */

.breadcrumb {
  display: flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-sans);
  font-size: 0.85rem;
  margin-bottom: 24px;
  padding: 8px 0;
  border-bottom: 1px solid var(--color-border);
}

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

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

.breadcrumb-sep {
  color: #95a5a6;
}

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

/* ==========================================================================
   页面标题区
   ========================================================================== */

.page-header {
  margin-bottom: 40px;
  padding-bottom: 24px;
  border-bottom: 2px solid var(--color-primary);
}

.page-title {
  font-size: 2rem;
  margin-bottom: 12px;
}

.page-description {
  font-size: 1.05rem;
  color: var(--color-text);
  max-width: 760px;
  line-height: 1.8;
}

/* ==========================================================================
   通用 section
   ========================================================================== */

.section-title {
  font-size: 1.5rem;
  margin-bottom: 8px;
  position: relative;
  padding-left: 16px;
}

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

.section-desc,
.section-description {
  font-size: 0.95rem;
  color: var(--color-text);
  margin-bottom: 24px;
  max-width: 720px;
}

/* ==========================================================================
   首页：时间线首屏
   ========================================================================== */

.timeline-section {
  background-color: var(--color-white);
  border-radius: var(--radius);
  padding: 40px 32px;
  margin-bottom: 32px;
  border-top: 3px solid var(--color-primary);
}

.home-h1 {
  font-size: 2.25rem;
  margin-bottom: 16px;
  text-align: center;
}

.hero-media {
  margin: 24px auto 32px;
  max-width: 960px;
}

.hero-figure {
  border-radius: var(--radius);
  overflow: hidden;
  background-color: var(--color-bg);
}

.hero-figure img {
  width: 100%;
  height: 420px;
  object-fit: cover;
}

.timeline-section .section-desc {
  text-align: center;
  margin: 0 auto 32px;
}

.timeline-list {
  position: relative;
  padding-left: 32px;
}

.timeline-list::before {
  content: "";
  position: absolute;
  left: 8px;
  top: 0;
  bottom: 0;
  width: 2px;
  background-color: var(--color-border);
}

.timeline-item {
  position: relative;
  margin-bottom: 28px;
}

.timeline-item::before {
  content: "";
  position: absolute;
  left: -32px;
  top: 8px;
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background-color: var(--color-accent);
  border: 2px solid var(--color-white);
  box-shadow: 0 0 0 2px var(--color-accent);
}

.timeline-entry {
  background-color: var(--color-bg-light);
  border-radius: var(--radius);
  padding: 20px 24px;
  border-left: 3px solid var(--color-primary);
}

.timeline-entry:hover {
  border-left-color: var(--color-accent);
}

.entry-title {
  font-size: 1.1rem;
  margin-bottom: 6px;
}

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

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

.entry-summary {
  font-size: 0.95rem;
  margin-bottom: 8px;
  line-height: 1.7;
}

.entry-date {
  font-family: var(--font-sans);
  font-size: 0.85rem;
  color: #7f8c8d;
  font-style: italic;
}

/* ==========================================================================
   首页：频道导航带
   ========================================================================== */

.channel-nav-section {
  margin-bottom: 32px;
}

.channel-shell {
  background-color: var(--color-white);
  border-radius: var(--radius);
  padding: 32px;
}

.channel-tag-list {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 16px;
}

.channel-tag-list li a {
  display: block;
  padding: 16px 20px;
  background-color: var(--color-bg-light);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  font-family: var(--font-sans);
  font-weight: 600;
  text-align: center;
  color: var(--color-primary);
  transition: all var(--transition);
}

.channel-tag-list li a:hover {
  background-color: var(--color-primary);
  color: var(--color-white);
  border-color: var(--color-primary);
}

/* ==========================================================================
   首页：焦点专题与短讯并列
   ========================================================================== */

.focus-short-section {
  margin-bottom: 32px;
}

.focus-short-shell {
  display: grid;
  grid-template-columns: 1.2fr 0.8fr;
  gap: 24px;
  align-items: start;
}

.focus-card,
.short-news-list {
  background-color: var(--color-white);
  border-radius: var(--radius);
  padding: 28px;
}

.feature-topic {
  margin-top: 16px;
}

.feature-topic img {
  width: 100%;
  height: 240px;
  object-fit: cover;
  border-radius: var(--radius);
  margin-bottom: 16px;
}

.topic-title {
  font-size: 1.25rem;
  margin-bottom: 8px;
}

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

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

.topic-summary {
  font-size: 0.95rem;
  line-height: 1.7;
}

.short-news-list .short-items {
  margin-top: 16px;
}

.short-item {
  padding: 12px 0;
  border-bottom: 1px solid var(--color-border);
}

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

.short-item a {
  display: block;
  font-family: var(--font-sans);
  font-size: 0.95rem;
  line-height: 1.5;
  color: var(--color-text);
  padding-left: 16px;
  position: relative;
}

.short-item a::before {
  content: "›";
  position: absolute;
  left: 0;
  color: var(--color-accent);
  font-weight: 700;
}

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

/* ==========================================================================
   首页：分类流
   ========================================================================== */

.category-flow-section {
  margin-bottom: 32px;
}

.category-shell {
  background-color: var(--color-white);
  border-radius: var(--radius);
  padding: 32px;
}

.category-group {
  margin-bottom: 28px;
  padding-bottom: 24px;
  border-bottom: 1px solid var(--color-border);
}

.category-group:last-child {
  margin-bottom: 0;
  padding-bottom: 0;
  border-bottom: none;
}

.group-title {
  font-size: 1.125rem;
  margin-bottom: 12px;
  color: var(--color-primary);
  padding-left: 12px;
  border-left: 3px solid var(--color-accent);
}

.group-list li {
  margin-bottom: 8px;
  padding-left: 20px;
  position: relative;
}

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

.group-list li a {
  font-size: 0.95rem;
  color: var(--color-text);
  font-family: var(--font-sans);
}

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

/* ==========================================================================
   首页：编辑推荐
   ========================================================================== */

.editor-picks-section {
  margin-bottom: 32px;
}

.picks-shell {
  background-color: var(--color-white);
  border-radius: var(--radius);
  padding: 32px;
}

.picks-list {
  display: grid;
  gap: 16px;
}

.pick-item {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 16px;
  align-items: baseline;
  padding: 20px 24px;
  background-color: var(--color-bg-light);
  border-radius: var(--radius);
  border-left: 3px solid var(--color-accent);
}

.pick-title {
  font-size: 1.05rem;
  margin-bottom: 4px;
}

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

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

.pick-reason {
  font-size: 0.9rem;
  color: var(--color-text);
  font-style: italic;
  margin: 0;
}

/* ==========================================================================
   首页：信息来源与反馈
   ========================================================================== */

.source-feedback-section {
  margin-bottom: 0;
}

.source-shell {
  background-color: var(--color-white);
  border-radius: var(--radius);
  padding: 32px;
  border-left: 4px solid var(--color-primary);
}

.source-note {
  background-color: var(--color-bg-light);
  padding: 20px 24px;
  border-radius: var(--radius);
  margin-bottom: 16px;
}

.source-note p {
  font-size: 0.95rem;
  margin: 0;
  line-height: 1.7;
}

.feedback-link a {
  display: inline-block;
  font-family: var(--font-sans);
  font-weight: 600;
  color: var(--color-accent);
  border-bottom: 2px solid var(--color-accent);
  padding-bottom: 2px;
}

.feedback-link a:hover {
  color: var(--color-primary);
  border-bottom-color: var(--color-primary);
}

/* ==========================================================================
   内页：频道分类
   ========================================================================== */

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

.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);
  transition: box-shadow var(--transition);
}

.channel-card:hover {
  box-shadow: 0 4px 16px rgba(44, 62, 80, 0.1);
}

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

.channel-card-body {
  padding: 24px;
}

.channel-name {
  font-size: 1.25rem;
  margin-bottom: 8px;
}

.channel-desc {
  font-size: 0.95rem;
  line-height: 1.7;
  margin-bottom: 12px;
}

.channel-card-body a {
  font-family: var(--font-sans);
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--color-accent);
  display: inline-flex;
  align-items: center;
  gap: 4px;
}

.channel-card-body a:hover {
  color: var(--color-primary);
}

.channel-card-body a span {
  transition: transform var(--transition);
}

.channel-card-body a:hover span {
  transform: translateX(4px);
}

.channel-notes {
  margin-bottom: 40px;
}

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

.note-item {
  background-color: var(--color-white);
  border-radius: var(--radius);
  padding: 24px;
  border-top: 3px solid var(--color-primary);
}

.note-title {
  font-size: 1.05rem;
  margin-bottom: 8px;
}

.note-item p {
  font-size: 0.9rem;
  line-height: 1.7;
  margin: 0;
}

/* ==========================================================================
   内页：相关推荐
   ========================================================================== */

.related-links {
  background-color: var(--color-white);
  border-radius: var(--radius);
  padding: 24px 28px;
  margin-bottom: 40px;
}

.related-heading {
  font-size: 1.125rem;
  margin-bottom: 16px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--color-border);
}

.related-links ul li {
  margin-bottom: 8px;
  padding-left: 16px;
  position: relative;
}

.related-links ul li::before {
  content: "→";
  position: absolute;
  left: 0;
  color: var(--color-accent);
}

.related-links ul li a {
  font-family: var(--font-sans);
  font-size: 0.95rem;
  color: var(--color-text);
}

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

/* ==========================================================================
   内页：内容专题
   ========================================================================== */

.topic-list-section {
  margin-bottom: 40px;
}

.topic-grid {
  display: grid;
  grid-template-columns: repeat(3, 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);
}

.topic-card:hover {
  box-shadow: 0 4px 16px rgba(44, 62, 80, 0.1);
}

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

.topic-body {
  padding: 20px 24px;
}

.topic-title {
  font-size: 1.1rem;
  margin-bottom: 8px;
}

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

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

.topic-summary {
  font-size: 0.9rem;
  line-height: 1.7;
  margin-bottom: 12px;
}

.topic-readmore {
  margin: 0;
}

.topic-readmore a {
  font-family: var(--font-sans);
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--color-accent);
}

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

.topic-summary-section {
  margin-bottom: 40px;
}

.summary-list {
  display: grid;
  gap: 20px;
}

.summary-item {
  background-color: var(--color-white);
  border-radius: var(--radius);
  padding: 24px 28px;
  border-left: 3px solid var(--color-primary);
}

.summary-title {
  font-size: 1.05rem;
  margin-bottom: 8px;
}

.summary-text {
  font-size: 0.95rem;
  line-height: 1.7;
  margin-bottom: 12px;
}

.summary-extend {
  display: flex;
  gap: 24px;
  margin: 0;
}

.summary-extend a {
  font-family: var(--font-sans);
  font-size: 0.85rem;
  color: var(--color-accent);
}

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

/* ==========================================================================
   内页：深度解读
   ========================================================================== */

.article-summary {
  background-color: var(--color-white);
  border-radius: var(--radius);
  padding: 28px 32px;
  margin-bottom: 32px;
  border-left: 4px solid var(--color-accent);
  font-style: italic;
}

.article-summary p {
  font-size: 1.05rem;
  line-height: 1.8;
  margin: 0;
}

.article-section {
  background-color: var(--color-white);
  border-radius: var(--radius);
  padding: 32px;
  margin-bottom: 32px;
}

.article-section h2 {
  margin-bottom: 16px;
}

.article-section p {
  font-size: 1rem;
  line-height: 1.8;
}

.article-figure {
  margin: 24px 0;
  border-radius: var(--radius);
  overflow: hidden;
  background-color: var(--color-bg-light);
}

.article-figure img {
  width: 100%;
  height: 360px;
  object-fit: cover;
}

.article-figure figcaption {
  padding: 12px 16px;
  font-family: var(--font-sans);
  font-size: 0.85rem;
  color: #7f8c8d;
  background-color: var(--color-bg-light);
  font-style: italic;
}

.related-reading {
  background-color: var(--color-white);
  border-radius: var(--radius);
  padding: 28px 32px;
}

.related-reading h2 {
  margin-bottom: 16px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--color-border);
}

.related-list li {
  margin-bottom: 10px;
  padding-left: 20px;
  position: relative;
}

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

.related-list li a {
  font-family: var(--font-sans);
  color: var(--color-text);
}

.related-list li a:hover {
  color: var(--color-accent);
}

/* ==========================================================================
   内页：实用指南
   ========================================================================== */

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

.guide-section {
  background-color: var(--color-white);
  border-radius: var(--radius);
  padding: 28px 32px;
  margin-bottom: 24px;
}

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

.method-item {
  background-color: var(--color-bg-light);
  border-radius: var(--radius);
  padding: 20px 24px;
  border-top: 3px solid var(--color-primary);
}

.method-item h3 {
  font-size: 1rem;
  margin-bottom: 8px;
}

.method-item p {
  font-size: 0.9rem;
  line-height: 1.7;
  margin-bottom: 8px;
}

.method-item p:last-child {
  margin-bottom: 0;
}

.method-item a {
  font-family: var(--font-sans);
  font-size: 0.85rem;
  color: var(--color-accent);
}

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

.guide-figure {
  margin: 24px 0;
  border-radius: var(--radius);
  overflow: hidden;
  background-color: var(--color-white);
}

.guide-figure img {
  width: 100%;
  height: 360px;
  object-fit: cover;
}

.guide-figure figcaption {
  padding: 12px 16px;
  font-family: var(--font-sans);
  font-size: 0.85rem;
  color: #7f8c8d;
  background-color: var(--color-bg-light);
  font-style: italic;
}

.guide-related {
  background-color: var(--color-white);
  border-radius: var(--radius);
  padding: 24px 28px;
  margin-top: 24px;
}

.related-title {
  font-size: 1.125rem;
  margin-bottom: 16px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--color-border);
}

.guide-related ul li {
  margin-bottom: 8px;
  padding-left: 16px;
  position: relative;
}

.guide-related ul li::before {
  content: "→";
  position: absolute;
  left: 0;
  color: var(--color-accent);
}

.guide-related ul li a {
  font-family: var(--font-sans);
  font-size: 0.95rem;
  color: var(--color-text);
}

.guide-related ul li a:hover {
  color: var(--color-accent);
}

/* ==========================================================================
   内页：常见问题
   ========================================================================== */

.faq-categories {
  background-color: var(--color-white);
  border-radius: var(--radius);
  padding: 28px 32px;
  margin-bottom: 32px;
}

.faq-categories h2 {
  margin-bottom: 16px;
}

.content-media-inline {
  margin: 16px 0 20px;
  border-radius: var(--radius);
  overflow: hidden;
  background-color: var(--color-bg-light);
}

.content-media-inline img {
  width: 100%;
  height: 300px;
  object-fit: cover;
}

.content-media-inline figcaption {
  padding: 10px 16px;
  font-family: var(--font-sans);
  font-size: 0.85rem;
  color: #7f8c8d;
  background-color: var(--color-bg-light);
  font-style: italic;
}

.faq-categories > p {
  font-size: 0.95rem;
  line-height: 1.7;
}

.category-list {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
  margin-top: 20px;
}

.category-list li a {
  display: block;
  padding: 14px 20px;
  background-color: var(--color-bg-light);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  font-family: var(--font-sans);
  font-weight: 600;
  text-align: center;
  color: var(--color-primary);
}

.category-list li a:hover {
  background-color: var(--color-primary);
  color: var(--color-white);
  border-color: var(--color-primary);
}

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

.faq-group {
  background-color: var(--color-white);
  border-radius: var(--radius);
  padding: 28px 32px;
  margin-bottom: 24px;
}

.faq-group > h3 {
  font-size: 1.125rem;
  margin-bottom: 16px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--color-border);
}

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

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

.faq-item summary {
  padding: 16px 20px;
  cursor: pointer;
  font-family: var(--font-sans);
  font-weight: 600;
  font-size: 0.95rem;
  color: var(--color-primary);
  list-style: none;
  position: relative;
  padding-right: 40px;
}

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

.faq-item summary::after {
  content: "+";
  position: absolute;
  right: 20px;
  top: 50%;
  transform: translateY(-50%);
  font-size: 1.25rem;
  color: var(--color-accent);
}

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

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

.faq-item p {
  padding: 0 20px 16px;
  font-size: 0.95rem;
  line-height: 1.7;
  margin: 0;
}

.faq-item p a {
  color: var(--color-accent);
  font-family: var(--font-sans);
  font-size: 0.9rem;
}

.faq-item p a:hover {
  color: var(--color-primary);
  text-decoration: underline;
}

.self-service {
  background-color: var(--color-white);
  border-radius: var(--radius);
  padding: 28px 32px;
  margin-bottom: 32px;
}

.self-service h2 {
  margin-bottom: 12px;
}

.self-service > p {
  font-size: 0.95rem;
  line-height: 1.7;
}

.self-service ul {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 12px;
  margin-top: 16px;
}

.self-service ul li {
  padding: 12px 16px;
  background-color: var(--color-bg-light);
  border-radius: var(--radius);
  font-family: var(--font-sans);
  font-size: 0.9rem;
  border-left: 3px solid var(--color-primary);
}

.feedback-path {
  background-color: var(--color-white);
  border-radius: var(--radius);
  padding: 28px 32px;
  border-left: 4px solid var(--color-accent);
}

.feedback-path h2 {
  margin-bottom: 12px;
}

.feedback-path p {
  font-size: 0.95rem;
  line-height: 1.7;
}

.feedback-path p a {
  color: var(--color-accent);
  font-family: var(--font-sans);
  font-weight: 600;
}

.feedback-path p a:hover {
  color: var(--color-primary);
  text-decoration: underline;
}

/* ==========================================================================
   404 页面
   ========================================================================== */

.error-main {
  max-width: var(--container-width);
  margin: 0 auto;
  padding: 48px 24px;
  min-height: 60vh;
  display: flex;
  align-items: center;
  justify-content: center;
}

.error-content {
  background-color: var(--color-white);
  border-radius: var(--radius);
  padding: 48px 40px;
  text-align: center;
  max-width: 600px;
  width: 100%;
  border-top: 4px solid var(--color-primary);
}

.error-code {
  font-family: var(--font-sans);
  font-size: 4rem;
  font-weight: 700;
  color: var(--color-accent);
  line-height: 1;
  margin-bottom: 16px;
}

.error-heading {
  font-size: 1.5rem;
  margin-bottom: 12px;
}

.error-desc {
  font-size: 1rem;
  line-height: 1.7;
  margin-bottom: 24px;
}

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

.btn-home,
.btn-channel {
  display: inline-block;
  padding: 12px 24px;
  border-radius: var(--radius);
  font-family: var(--font-sans);
  font-weight: 600;
  font-size: 0.95rem;
  transition: all var(--transition);
}

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

.btn-home:hover {
  background-color: var(--color-accent);
  color: var(--color-white);
}

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

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

.error-tip {
  font-size: 0.9rem;
  color: #7f8c8d;
  margin: 0;
}

.error-tip a {
  color: var(--color-accent);
}

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

/* ==========================================================================
   响应式
   ========================================================================== */

@media (max-width: 1024px) {
  .topic-grid {
    grid-template-columns: repeat(2, 1fr);
  }

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

  .hero-figure img {
    height: 360px;
  }
}

@media (max-width: 768px) {
  .header-shell {
    padding: 0 16px;
    min-height: 56px;
  }

  .nav-toggle {
    display: block;
  }

  .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, 0.08);
  }

  .site-nav .nav-list {
    display: none;
    flex-direction: column;
    padding: 16px;
    gap: 4px;
  }

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

  .site-nav .nav-list li a {
    padding: 12px 16px;
    font-size: 1rem;
  }

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

  .home-h1 {
    font-size: 1.75rem;
  }

  .timeline-section {
    padding: 24px 20px;
  }

  .hero-figure img {
    height: 240px;
  }

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

  .focus-short-shell {
    grid-template-columns: 1fr;
  }

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

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

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

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

  .self-service ul {
    grid-template-columns: 1fr;
  }

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

  .footer-shell {
    padding: 32px 16px 16px;
  }

  .article-figure img,
  .guide-figure img,
  .content-media-inline img {
    height: 240px;
  }

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

  .summary-extend {
    flex-direction: column;
    gap: 8px;
  }

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

  .error-actions {
    flex-direction: column;
  }
}

@media (max-width: 480px) {
  .brand-name {
    font-size: 1.05rem;
  }

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

  .timeline-list {
    padding-left: 24px;
  }

  .timeline-item::before {
    left: -24px;
  }

  .timeline-entry {
    padding: 16px;
  }

  .channel-shell,
  .category-shell,
  .picks-shell,
  .source-shell {
    padding: 20px;
  }

  .focus-card,
  .short-news-list {
    padding: 20px;
  }

  .article-section,
  .faq-group,
  .self-service,
  .feedback-path {
    padding: 20px;
  }

  .guide-section {
    padding: 20px;
  }

  .faq-item summary {
    padding: 14px 16px;
    padding-right: 36px;
    font-size: 0.9rem;
  }

  .faq-item p {
    padding: 0 16px 14px;
  }
}