/* ============================================================
   base / 基础样式
   ============================================================ */
:root {
  --color-text: #1a1a1a;
  --color-bg: #f5f5f5;
  --color-link: #0056b3;
  --color-accent: #ff6600;
  --color-card: #ffffff;
  --color-border: #e0e0e0;
  --color-muted: #666666;
  --color-light: #fafafa;
  --font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Segoe UI", Roboto, sans-serif;
  --container-width: 1200px;
  --content-width: 760px;
  --radius: 8px;
  --radius-sm: 4px;
  --transition: 0.2s ease;
  --shadow: 0 1px 3px rgba(0, 0, 0, 0.08);
}

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

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

body {
  font-family: var(--font-family);
  font-size: 1rem;
  line-height: 1.6;
  color: var(--color-text);
  background-color: var(--color-bg);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

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

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

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

h1, h2, h3, h4, h5, h6 {
  font-weight: 700;
  line-height: 1.3;
  color: var(--color-text);
}

h1 {
  font-size: 2rem;
}

h2 {
  font-size: 1.5rem;
}

h3 {
  font-size: 1.125rem;
}

p {
  margin-bottom: 0.75rem;
}

ul, ol {
  list-style-position: inside;
  margin-bottom: 0.75rem;
}

/* ============================================================
   layout / 布局骨架
   ============================================================ */

/* 站点主体骨架 */
.site-body {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

.site-home .site-main,
.site-inner .site-main {
  flex: 1 0 auto;
}

/* 统一内容容器 */
.header-inner,
.footer-inner,
.home-main,
.inner-main {
  width: 100%;
  max-width: var(--container-width);
  margin: 0 auto;
  padding-left: 24px;
  padding-right: 24px;
}

/* ============================================================
   components / 页头与导航
   ============================================================ */

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

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 64px;
  padding-top: 8px;
  padding-bottom: 8px;
  gap: 16px;
}

.brand {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--color-text);
  text-decoration: none;
  white-space: nowrap;
  letter-spacing: 0.02em;
}

.brand:hover {
  color: var(--color-accent);
  text-decoration: none;
}

.brand-slogan {
  font-size: 0.875rem;
  color: var(--color-muted);
  margin: 0;
  white-space: nowrap;
}

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

.nav-list {
  display: flex;
  list-style: none;
  margin: 0;
  padding: 0;
  gap: 4px;
}

.nav-list li {
  margin: 0;
}

.nav-list a {
  display: block;
  padding: 8px 14px;
  font-size: 0.9375rem;
  color: var(--color-text);
  border-radius: var(--radius-sm);
  text-decoration: none;
  transition: background-color var(--transition), color var(--transition);
}

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

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

.nav-toggle {
  display: none;
  background: none;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  width: 44px;
  height: 44px;
  cursor: pointer;
  position: relative;
  padding: 0;
}

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

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

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

.nav-toggle[aria-expanded="true"]::before {
  transform: translateY(5px) rotate(45deg);
}

.nav-toggle[aria-expanded="true"]::after {
  transform: translateY(-5px) rotate(-45deg);
}

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

.breadcrumb {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 8px;
  padding: 16px 0;
  font-size: 0.875rem;
  color: var(--color-muted);
}

.breadcrumb a {
  color: var(--color-link);
  text-decoration: none;
}

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

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

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

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

.page-header {
  padding: 32px 0 24px;
  border-bottom: 1px solid var(--color-border);
  margin-bottom: 32px;
}

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

.page-description {
  font-size: 1.0625rem;
  color: var(--color-muted);
  max-width: var(--content-width);
  line-height: 1.7;
}

/* ============================================================
   components / 通用区块标题
   ============================================================ */

.section-title {
  font-size: 1.5rem;
  margin-bottom: 8px;
}

.section-desc {
  color: var(--color-muted);
  margin-bottom: 20px;
  max-width: var(--content-width);
}

.section-lead {
  color: var(--color-muted);
  margin-bottom: 24px;
  max-width: var(--content-width);
}

/* ============================================================
   components / 首页 - 焦点区
   ============================================================ */

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

.hero-content h1 {
  font-size: 2rem;
  margin-bottom: 16px;
  line-height: 1.3;
}

.hero-lead {
  font-size: 1.125rem;
  line-height: 1.7;
  color: var(--color-muted);
  margin-bottom: 24px;
}

.cta-link {
  display: inline-block;
  background-color: var(--color-accent);
  color: #fff;
  padding: 12px 28px;
  border-radius: var(--radius-sm);
  font-weight: 600;
  text-decoration: none;
  transition: background-color var(--transition);
}

.cta-link:hover {
  background-color: #e65c00;
  color: #fff;
  text-decoration: none;
}

.hero-media {
  margin: 0;
  border-radius: var(--radius);
  overflow: hidden;
  background-color: var(--color-border);
}

.hero-media img {
  width: 100%;
  height: 100%;
  min-height: 260px;
  object-fit: cover;
  aspect-ratio: 4 / 3;
}

/* ============================================================
   components / 首页 - 频道导航带
   ============================================================ */

.channel-nav-section {
  padding: 40px 0;
  border-top: 1px solid var(--color-border);
}

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

.channel-tag {
  display: inline-block;
  padding: 10px 20px;
  background-color: var(--color-card);
  border: 1px solid var(--color-border);
  border-radius: 999px;
  color: var(--color-text);
  font-size: 0.9375rem;
  text-decoration: none;
  transition: border-color var(--transition), color var(--transition), background-color var(--transition);
}

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

/* ============================================================
   components / 首页 - 最新资讯列表
   ============================================================ */

.latest-news {
  padding: 40px 0;
  border-top: 1px solid var(--color-border);
}

.news-list {
  display: flex;
  flex-direction: column;
  gap: 0;
}

.news-item {
  padding: 20px 0;
  border-bottom: 1px solid var(--color-border);
  display: grid;
  grid-template-columns: 1fr;
  gap: 4px;
}

.news-item:first-child {
  border-top: 1px solid var(--color-border);
}

.news-item h3 {
  font-size: 1.125rem;
  margin-bottom: 4px;
}

.news-item h3 a {
  color: var(--color-text);
  text-decoration: none;
}

.news-item h3 a:hover {
  color: var(--color-accent);
  text-decoration: underline;
}

.news-meta {
  font-size: 0.8125rem;
  color: var(--color-muted);
  margin-bottom: 6px;
}

.news-summary {
  font-size: 0.9375rem;
  color: var(--color-muted);
  line-height: 1.7;
  margin-bottom: 0;
}

.more-link {
  display: inline-block;
  margin-top: 20px;
  font-weight: 600;
}

/* ============================================================
   components / 首页 - 专题推荐区
   ============================================================ */

.topic-feature {
  padding: 40px 0;
  border-top: 1px solid var(--color-border);
}

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

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

.topic-media {
  margin: 0;
  background-color: var(--color-border);
  overflow: hidden;
}

.topic-media img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  aspect-ratio: 16 / 9;
}

.topic-card h3 {
  padding: 16px 16px 0;
  font-size: 1.125rem;
}

.topic-card h3 a {
  color: var(--color-text);
  text-decoration: none;
}

.topic-card h3 a:hover {
  color: var(--color-accent);
  text-decoration: underline;
}

.topic-card p {
  padding: 8px 16px 16px;
  color: var(--color-muted);
  font-size: 0.9375rem;
  line-height: 1.7;
  margin: 0;
}

/* ============================================================
   components / 首页 - 编辑推荐
   ============================================================ */

.editor-picks {
  padding: 40px 0;
  border-top: 1px solid var(--color-border);
}

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

.pick-item {
  background-color: var(--color-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 20px 24px;
}

.pick-item h3 {
  font-size: 1.125rem;
  margin-bottom: 6px;
}

.pick-item h3 a {
  color: var(--color-text);
  text-decoration: none;
}

.pick-item h3 a:hover {
  color: var(--color-accent);
  text-decoration: underline;
}

.pick-reason {
  color: var(--color-muted);
  font-size: 0.9375rem;
  line-height: 1.7;
  margin: 0;
}

/* ============================================================
   components / 首页 - 信息来源与反馈
   ============================================================ */

.source-info {
  padding: 40px 0;
  border-top: 1px solid var(--color-border);
  background-color: var(--color-light);
}

.source-info p {
  color: var(--color-muted);
  line-height: 1.8;
  max-width: var(--content-width);
}

/* ============================================================
   components / 频道分类页
   ============================================================ */

.channel-grid {
  padding-bottom: 32px;
}

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

.channel-card {
  background-color: var(--color-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 24px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.channel-card img {
  width: 48px;
  height: 48px;
  object-fit: contain;
  margin-bottom: 8px;
}

.channel-card h3 {
  font-size: 1.125rem;
}

.channel-card p {
  color: var(--color-muted);
  font-size: 0.9375rem;
  line-height: 1.7;
  flex: 1;
  margin-bottom: 12px;
}

.channel-card a {
  font-weight: 600;
  font-size: 0.9375rem;
}

.channel-notes {
  padding: 32px 0;
  border-top: 1px solid var(--color-border);
}

.notes-content {
  max-width: var(--content-width);
}

.notes-content p {
  color: var(--color-muted);
  line-height: 1.8;
}

/* ============================================================
   components / 内容专题页
   ============================================================ */

.topic-list {
  display: flex;
  flex-direction: column;
  gap: 24px;
  padding-bottom: 32px;
}

.topic-list .topic-card {
  flex-direction: row;
  align-items: stretch;
  overflow: hidden;
}

.topic-list .topic-media {
  flex: 0 0 240px;
}

.topic-list .topic-media img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  aspect-ratio: auto;
}

.topic-body {
  flex: 1;
  padding: 20px 24px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.topic-body h3 {
  font-size: 1.25rem;
  padding: 0;
}

.topic-body p {
  padding: 0;
  color: var(--color-muted);
  line-height: 1.7;
  flex: 1;
}

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

.topic-intro {
  padding: 32px 0;
  border-top: 1px solid var(--color-border);
}

.topic-intro p {
  color: var(--color-muted);
  line-height: 1.8;
  max-width: var(--content-width);
}

/* ============================================================
   components / 侧栏与相关阅读
   ============================================================ */

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

.related-links h2 {
  font-size: 1.25rem;
  margin-bottom: 16px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--color-border);
}

.related-links ul {
  list-style: none;
  margin: 0;
  padding: 0;
}

.related-links li {
  margin-bottom: 12px;
}

.related-links li:last-child {
  margin-bottom: 0;
}

.related-links a {
  display: block;
  padding: 6px 0;
  color: var(--color-text);
  text-decoration: none;
  line-height: 1.6;
}

.related-links a:hover {
  color: var(--color-accent);
  text-decoration: underline;
}

/* ============================================================
   components / 深度解读页
   ============================================================ */

.layout-shell {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 300px;
  gap: 40px;
  align-items: start;
  padding-bottom: 40px;
}

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

.analysis-framework {
  margin-bottom: 40px;
}

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

.framework-steps .step-item {
  background-color: var(--color-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 20px;
}

.framework-steps .step-item h3 {
  font-size: 1.0625rem;
  margin-bottom: 8px;
  padding-left: 16px;
  border-left: 3px solid var(--color-accent);
}

.framework-steps .step-item p {
  color: var(--color-muted);
  font-size: 0.9375rem;
  line-height: 1.7;
  margin: 0;
}

.case-studies {
  padding-top: 32px;
  border-top: 1px solid var(--color-border);
}

.case-studies > p {
  color: var(--color-muted);
  max-width: var(--content-width);
}

.case-item {
  margin-top: 24px;
  background-color: var(--color-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 24px;
}

.case-media {
  margin: 0 0 16px;
  border-radius: var(--radius-sm);
  overflow: hidden;
  background-color: var(--color-border);
}

.case-media img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  aspect-ratio: 16 / 9;
}

.case-item h3 {
  font-size: 1.125rem;
  margin-bottom: 12px;
}

.case-item p {
  color: var(--color-muted);
  font-size: 0.9375rem;
  line-height: 1.7;
}

.case-item p strong {
  color: var(--color-text);
  font-weight: 600;
}

/* ============================================================
   components / 实用指南页
   ============================================================ */

.guide-intro {
  display: grid;
  grid-template-columns: 300px 1fr;
  gap: 32px;
  align-items: start;
  margin-bottom: 40px;
}

.guide-hero {
  margin: 0;
  border-radius: var(--radius);
  overflow: hidden;
  background-color: var(--color-border);
}

.guide-hero img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  aspect-ratio: 4 / 3;
}

.guide-hero figcaption {
  padding: 8px 12px;
  font-size: 0.8125rem;
  color: var(--color-muted);
  background-color: var(--color-card);
}

.guide-intro > p {
  color: var(--color-muted);
  line-height: 1.8;
  margin: 0;
  align-self: center;
}

.guide-section {
  margin-bottom: 40px;
  padding-top: 32px;
  border-top: 1px solid var(--color-border);
}

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

.step-list .step-item {
  display: flex;
  gap: 20px;
  background-color: var(--color-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 20px 24px;
}

.step-number {
  flex: 0 0 44px;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background-color: var(--color-accent);
  color: #fff;
  font-weight: 700;
  font-size: 1.125rem;
  display: flex;
  align-items: center;
  justify-content: center;
}

.step-content h3 {
  font-size: 1.125rem;
  margin-bottom: 8px;
}

.step-content p {
  color: var(--color-muted);
  font-size: 0.9375rem;
  line-height: 1.7;
  margin-bottom: 6px;
}

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

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

.tool-item {
  background-color: var(--color-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 24px;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.tool-icon {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-sm);
  background-color: var(--color-light);
  border: 1px solid var(--color-border);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
}

.tool-content h3 {
  font-size: 1.0625rem;
  margin-bottom: 8px;
}

.tool-content p {
  color: var(--color-muted);
  font-size: 0.9375rem;
  line-height: 1.7;
  margin: 0;
}

.guide-section#related p {
  color: var(--color-muted);
  line-height: 1.8;
  max-width: var(--content-width);
}

.guide-section#related a {
  font-weight: 600;
}

/* ============================================================
   components / 404 错误页
   ============================================================ */

.error-main {
  display: flex;
  align-items: center;
  justify-content: center;
  flex: 1;
  padding: 60px 24px;
}

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

.error-content h1 {
  font-size: 2rem;
  margin-bottom: 16px;
}

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

.error-desc {
  color: var(--color-muted);
  font-size: 1.0625rem;
  margin-bottom: 24px;
}

.error-btn {
  display: inline-block;
  background-color: var(--color-accent);
  color: #fff;
  padding: 12px 28px;
  border-radius: var(--radius-sm);
  font-weight: 600;
  text-decoration: none;
  transition: background-color var(--transition);
}

.error-btn:hover {
  background-color: #e65c00;
  color: #fff;
  text-decoration: none;
}

/* ============================================================
   components / 页脚
   ============================================================ */

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

.footer-inner {
  padding-top: 40px;
  padding-bottom: 24px;
}

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

.footer-name {
  font-size: 1.25rem;
  font-weight: 700;
  margin-bottom: 4px;
}

.footer-brand p:last-child {
  color: var(--color-muted);
  font-size: 0.9375rem;
  margin: 0;
}

.footer-links {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
  padding: 24px 0;
  border-top: 1px solid var(--color-border);
}

.footer-col h3 {
  font-size: 1rem;
  margin-bottom: 12px;
  color: var(--color-text);
}

.footer-col ul {
  list-style: none;
  margin: 0;
  padding: 0;
}

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

.footer-col a {
  color: var(--color-muted);
  font-size: 0.9375rem;
  text-decoration: none;
  transition: color var(--transition);
}

.footer-col a:hover {
  color: var(--color-accent);
  text-decoration: underline;
}

.footer-copy {
  border-top: 1px solid var(--color-border);
  padding-top: 16px;
  font-size: 0.8125rem;
  color: var(--color-muted);
  text-align: center;
  margin: 0;
}

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

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

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

  .layout-shell {
    grid-template-columns: minmax(0, 1fr) 260px;
    gap: 24px;
  }

  .guide-intro {
    grid-template-columns: 240px 1fr;
    gap: 24px;
  }
}

@media (max-width: 768px) {
  .header-inner {
    flex-wrap: wrap;
    min-height: 56px;
    padding-top: 8px;
    padding-bottom: 8px;
  }

  .brand-slogan {
    display: none;
  }

  .nav-toggle {
    display: block;
    order: 3;
  }

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

  .nav-list {
    display: none;
    flex-direction: column;
    width: 100%;
    background-color: var(--color-card);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: 8px;
    margin-top: 8px;
  }

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

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

  .hero-focus {
    grid-template-columns: 1fr;
    gap: 24px;
    padding: 32px 0;
  }

  .hero-content h1 {
    font-size: 1.625rem;
  }

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

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

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

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

  .topic-list .topic-media {
    flex: none;
  }

  .topic-list .topic-media img {
    aspect-ratio: 16 / 9;
  }

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

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

  .guide-intro {
    grid-template-columns: 1fr;
  }

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

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

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

  .page-title {
    font-size: 1.625rem;
  }
}

@media (max-width: 480px) {
  .header-inner {
    padding-left: 16px;
    padding-right: 16px;
  }

  .home-main,
  .inner-main {
    padding-left: 16px;
    padding-right: 16px;
  }

  .footer-inner {
    padding-left: 16px;
    padding-right: 16px;
  }

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

  .channel-tags {
    gap: 8px;
  }

  .channel-tag {
    padding: 8px 16px;
    font-size: 0.875rem;
  }

  .pick-item {
    padding: 16px;
  }

  .step-list .step-item {
    padding: 16px;
    gap: 14px;
  }

  .step-number {
    flex-basis: 36px;
    width: 36px;
    height: 36px;
    font-size: 1rem;
  }

  .case-item {
    padding: 16px;
  }

  .related-links {
    padding: 16px;
  }
}

/* ============================================================
   accessibility / 可访问性增强
   ============================================================ */

:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
  }
}