@import url('https://fonts.googleapis.com/css2?family=Plus+Jakarta+Sans:wght@300;400;500;600;700&display=swap');

/* =============================================
   CSS 变量 & 基础重置
   ============================================= */
:root {
  --c-black: #000000;
  --c-white: #ffffff;
  --c-gray-100: #f5f5f5;
  --c-gray-200: #e8e8e8;
  --c-gray-400: #999999;
  --c-gray-600: #555555;
  --c-gray-800: #222222;
  --c-accent: #000000;
  --c-accent-inv: #ffffff;

  --font-base: 'Plus Jakarta Sans', 'Helvetica Neue', Helvetica, Arial, sans-serif;

  --space-1: 8px;
  --space-2: 16px;
  --space-3: 24px;
  --space-4: 32px;
  --space-5: 48px;
  --space-6: 64px;
  --space-7: 96px;
  --space-8: 128px;

  --nav-width: 240px;
  --radius-card: 28px;
  --radius-sm: 8px;

  --transition-fast: 0.18s ease;
  --transition-med: 0.32s ease;
}

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

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

body {
  font-family: var(--font-base);
  font-size: 1rem;
  line-height: 1.6;
  color: var(--c-black);
  background: var(--c-white);
  -webkit-font-smoothing: antialiased;
}

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

a {
  color: inherit;
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

ul, ol {
  list-style: none;
}

/* =============================================
   页面骨架：左侧固定导航 + 右侧内容
   ============================================= */
.page-shell {
  display: flex;
  min-height: 100vh;
}

/* =============================================
   左侧固定导航
   ============================================= */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  width: var(--nav-width);
  height: 100vh;
  background: var(--c-black);
  color: var(--c-white);
  display: flex;
  flex-direction: column;
  align-items: stretch;
  z-index: 100;
  overflow-y: auto;
}

.site-header__brand {
  padding: var(--space-3);
  border-bottom: 1px solid rgba(255,255,255,0.12);
  flex-shrink: 0;
}

.brand-link {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  background: var(--c-white);
  color: var(--c-black);
  font-weight: 700;
  font-size: 1.25rem;
  letter-spacing: -0.02em;
  border-radius: var(--radius-sm);
  transition: opacity var(--transition-fast);
}

.brand-link:hover {
  opacity: 0.85;
  text-decoration: none;
}

.site-logo-mark {
  width: 40px;
  height: 40px;
  object-fit: contain;
}

.site-logo-text {
  line-height: 1;
}

.site-nav {
  display: flex;
  flex-direction: column;
  padding: var(--space-2) 0;
  flex: 1;
}

.nav-link {
  display: block;
  padding: var(--space-2) var(--space-3);
  font-size: 0.8125rem;
  font-weight: 500;
  color: rgba(255,255,255,0.72);
  line-height: 1.4;
  border-left: 2px solid transparent;
  transition: color var(--transition-fast), border-color var(--transition-fast), background var(--transition-fast);
  min-height: 44px;
  display: flex;
  align-items: center;
}

.nav-link:hover {
  color: var(--c-white);
  background: rgba(255,255,255,0.07);
  border-left-color: rgba(255,255,255,0.4);
  text-decoration: none;
}

.nav-link--active {
  color: var(--c-white);
  border-left-color: var(--c-white);
  background: rgba(255,255,255,0.1);
  font-weight: 700;
}

.site-header__tagline {
  padding: var(--space-2) var(--space-3);
  border-top: 1px solid rgba(255,255,255,0.12);
  font-size: 0.6875rem;
  color: rgba(255,255,255,0.4);
  line-height: 1.5;
  flex-shrink: 0;
}

/* =============================================
   主内容区
   ============================================= */
.page-main {
  margin-left: var(--nav-width);
  flex: 1;
  min-width: 0;
}

.wrap {
  max-width: 960px;
  margin: 0 auto;
  padding: 0 var(--space-4);
}

/* =============================================
   Hero 区 — 首页
   ============================================= */
.hero-section {
  min-height: 100vh;
  display: grid;
  grid-template-columns: 1fr 1fr;
  align-items: center;
  gap: var(--space-6);
  padding: var(--space-6) 0;
  position: relative;
  overflow: hidden;
}

.hero-content {
  position: relative;
  z-index: 2;
}

.hero-eyebrow,
.section-eyebrow,
.article-eyebrow,
.hero-eyebrow.card-eyebrow {
  display: block;
  font-size: 0.6875rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--c-gray-600);
  margin-bottom: var(--space-2);
}

.hero-title {
  font-size: clamp(2rem, 5vw, 3.5rem);
  font-weight: 700;
  line-height: 1.1;
  letter-spacing: -0.03em;
  color: var(--c-black);
  margin-bottom: var(--space-3);
}

.hero-desc {
  font-size: 1.0625rem;
  color: var(--c-gray-600);
  line-height: 1.65;
  margin-bottom: var(--space-4);
  max-width: 38ch;
}

.hero-cta {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  background: var(--c-black);
  color: var(--c-white);
  font-size: 0.875rem;
  font-weight: 600;
  padding: 14px var(--space-4);
  border-radius: var(--radius-sm);
  transition: background var(--transition-fast), transform var(--transition-fast);
  min-height: 48px;
}

.hero-cta:hover {
  background: var(--c-gray-800);
  text-decoration: none;
  transform: translateY(-1px);
}

.hero-grid-decoration {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
}

.grid-pattern {
  width: 100%;
  aspect-ratio: 1;
  background-image:
    linear-gradient(var(--c-gray-200) 1px, transparent 1px),
    linear-gradient(90deg, var(--c-gray-200) 1px, transparent 1px);
  background-size: 40px 40px;
  border-radius: var(--radius-card);
  position: relative;
}

.grid-pattern::after {
  content: '';
  position: absolute;
  inset: 15%;
  background: var(--c-black);
  border-radius: calc(var(--radius-card) - 8px);
  opacity: 0.06;
}

/* =============================================
   通用 section 标题
   ============================================= */
.section-title {
  font-size: clamp(1.25rem, 3vw, 2rem);
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--c-black);
  margin-bottom: var(--space-4);
}

.content-section,
.topics-section,
.timeline-section,
.related-section,
.children-section,
.about-nav-section,
.about-cta-section,
.related-topics,
.nav-hint-section,
.legal-nav-section {
  padding: var(--space-6) 0;
  border-top: 1px solid var(--c-gray-200);
}

/* =============================================
   散文正文样式
   ============================================= */
.prose {
  font-size: 1rem;
  line-height: 1.75;
  color: var(--c-gray-800);
}

.prose h2 {
  font-size: 1.375rem;
  font-weight: 700;
  color: var(--c-black);
  margin-top: var(--space-5);
  margin-bottom: var(--space-2);
  letter-spacing: -0.02em;
}

.prose h3 {
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--c-black);
  margin-top: var(--space-4);
  margin-bottom: var(--space-2);
}

.prose p {
  margin-bottom: var(--space-3);
}

.prose ul,
.prose ol {
  margin-bottom: var(--space-3);
  padding-left: var(--space-4);
  list-style: disc;
}

.prose ol {
  list-style: decimal;
}

.prose li {
  margin-bottom: var(--space-1);
  line-height: 1.65;
}

.prose a {
  color: var(--c-black);
  text-decoration: underline;
  text-underline-offset: 2px;
}

.prose strong {
  font-weight: 700;
}

.prose blockquote {
  border-left: 3px solid var(--c-black);
  padding-left: var(--space-3);
  margin: var(--space-4) 0;
  color: var(--c-gray-600);
  font-style: italic;
}

.prose table {
  width: 100%;
  border-collapse: collapse;
  margin-bottom: var(--space-4);
}

.prose th,
.prose td {
  padding: var(--space-2) var(--space-2);
  border: 1px solid var(--c-gray-200);
  text-align: left;
  font-size: 0.9375rem;
}

.prose th {
  background: var(--c-gray-100);
  font-weight: 600;
}

.prose--legal {
  font-size: 0.9375rem;
}

/* =============================================
   卡片
   ============================================= */
.card {
  border-radius: var(--radius-card);
  background: var(--c-white);
  border: 1px solid var(--c-gray-200);
  overflow: hidden;
  transition: border-color var(--transition-fast), transform var(--transition-fast), box-shadow var(--transition-fast);
  border-bottom: 3px solid var(--c-black);
}

.card:hover {
  border-color: var(--c-black);
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(0,0,0,0.08);
}

.card-inner {
  padding: var(--space-3) var(--space-3) var(--space-3);
}

.card-eyebrow {
  display: block;
  font-size: 0.6875rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--c-gray-400);
  margin-bottom: var(--space-1);
}

.card-title {
  font-size: 1rem;
  font-weight: 700;
  line-height: 1.35;
  margin-bottom: var(--space-1);
  letter-spacing: -0.01em;
}

.card-title a {
  color: var(--c-black);
  transition: color var(--transition-fast);
}

.card-title a:hover {
  color: var(--c-gray-600);
  text-decoration: none;
}

.card-title--sm {
  font-size: 0.9375rem;
}

.card-desc {
  font-size: 0.875rem;
  color: var(--c-gray-600);
  line-height: 1.55;
  margin-bottom: var(--space-1);
}

.card-date {
  display: block;
  font-size: 0.75rem;
  color: var(--c-gray-400);
  margin-top: var(--space-1);
  font-variant-numeric: tabular-nums;
}

.card-media {
  overflow: hidden;
  max-height: 180px;
}

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

.card--sm {
  border-radius: var(--radius-sm);
}

.card--list {
  display: flex;
  gap: 0;
  flex-direction: row;
}

.card--list .card-media {
  width: 120px;
  flex-shrink: 0;
  max-height: none;
}

.card--list .card-thumb {
  width: 120px;
  height: 100%;
  object-fit: cover;
}

/* =============================================
   时间线列表
   ============================================= */
.timeline-list {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: var(--space-3);
}

.timeline-item {
  opacity: 0;
  transform: translateY(16px);
  animation: fadeUp var(--transition-med) forwards;
  animation-delay: calc(var(--i, 0) * 0.07s);
}

@keyframes fadeUp {
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@media (prefers-reduced-motion: reduce) {
  .timeline-item {
    opacity: 1;
    transform: none;
    animation: none;
  }
}

/* =============================================
   话题网格
   ============================================= */
.topic-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: var(--space-3);
}

.topic-entry article {
  padding: var(--space-3);
  border: 1px solid var(--c-gray-200);
  border-radius: var(--radius-card);
  border-bottom: 3px solid var(--c-black);
  transition: border-color var(--transition-fast), transform var(--transition-fast);
  height: 100%;
}

.topic-entry article:hover {
  border-color: var(--c-black);
  transform: translateY(-2px);
}

.topic-entry h3 {
  font-size: 0.9375rem;
  font-weight: 700;
  margin-bottom: var(--space-1);
}

.topic-entry h3 a {
  color: var(--c-black);
}

.topic-entry h3 a:hover {
  text-decoration: underline;
}

.topic-entry p {
  font-size: 0.8125rem;
  color: var(--c-gray-600);
  line-height: 1.5;
  margin-bottom: var(--space-1);
}

.topic-count {
  font-size: 0.75rem;
  color: var(--c-gray-400);
  font-variant-numeric: tabular-nums;
}

/* =============================================
   Pill 标签
   ============================================= */
.pill-list {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-1);
}

.pill-list--lg {
  gap: var(--space-2);
}

.pill-link {
  display: inline-flex;
  align-items: center;
  padding: 8px var(--space-2);
  background: var(--c-gray-100);
  border: 1px solid var(--c-gray-200);
  border-radius: 100px;
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--c-black);
  transition: background var(--transition-fast), border-color var(--transition-fast);
  min-height: 40px;
}

.pill-link:hover {
  background: var(--c-black);
  color: var(--c-white);
  border-color: var(--c-black);
  text-decoration: none;
}

/* =============================================
   按钮
   ============================================= */
.btn-outline {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  border: 1.5px solid var(--c-black);
  color: var(--c-black);
  font-size: 0.875rem;
  font-weight: 600;
  padding: 12px var(--space-3);
  border-radius: var(--radius-sm);
  transition: background var(--transition-fast), color var(--transition-fast);
  min-height: 44px;
  white-space: nowrap;
}

.btn-outline:hover {
  background: var(--c-black);
  color: var(--c-white);
  text-decoration: none;
}

.nav-hint-links {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  align-items: center;
}

/* =============================================
   页面 Hero（内页）
   ============================================= */
.page-hero,
.about-hero,
.legal-hero {
  padding: var(--space-7) 0 var(--space-5);
  position: relative;
}

.page-hero--topic {
  border-bottom: 1px solid var(--c-gray-200);
}

.page-h1 {
  font-size: clamp(1.75rem, 4vw, 2.75rem);
  font-weight: 700;
  letter-spacing: -0.03em;
  line-height: 1.15;
  margin-bottom: var(--space-2);
  color: var(--c-black);
}

.page-intro {
  font-size: 1.0625rem;
  color: var(--c-gray-600);
  line-height: 1.65;
  max-width: 56ch;
}

/* =============================================
   About 页专属
   ============================================= */
.about-hero {
  display: grid;
  grid-template-columns: 1fr auto;
  align-items: start;
  gap: var(--space-5);
}

.about-decoration {
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
  padding-top: var(--space-5);
}

.geo-block {
  background: var(--c-black);
}

.geo-block--lg {
  width: 80px;
  height: 80px;
  border-radius: var(--radius-sm);
}

.geo-block--sm {
  width: 40px;
  height: 40px;
  border-radius: 4px;
  align-self: flex-end;
}

.cta-block {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-3);
}

.cta-text {
  font-size: 1.0625rem;
  color: var(--c-gray-800);
  font-weight: 500;
  flex: 1 1 100%;
  margin-bottom: var(--space-1);
}

/* =============================================
   文章页
   ============================================= */
.page-main--article .wrap {
  max-width: 720px;
}

.article-section {
  padding: var(--space-5) 0;
}

.breadcrumb {
  font-size: 0.8125rem;
  color: var(--c-gray-400);
  margin-bottom: var(--space-4);
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 4px;
}

.breadcrumb a {
  color: var(--c-gray-600);
  transition: color var(--transition-fast);
}

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

.article-header {
  margin-bottom: var(--space-5);
}

.article-title {
  font-size: clamp(1.5rem, 4vw, 2.5rem);
  font-weight: 700;
  letter-spacing: -0.03em;
  line-height: 1.15;
  margin-bottom: var(--space-2);
  color: var(--c-black);
}

.article-meta {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  align-items: center;
  font-size: 0.8125rem;
  color: var(--c-gray-400);
}

.article-date {
  font-variant-numeric: tabular-nums;
}

.article-updated {
  color: var(--c-gray-400);
}

.article-hero-media {
  margin-bottom: var(--space-4);
  border-radius: var(--radius-sm);
  overflow: hidden;
}

.article-hero-img {
  width: 100%;
  height: auto;
  display: block;
}

.article-content {
  margin-top: var(--space-4);
}

.article-eyebrow {
  display: block;
  font-size: 0.6875rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--c-gray-400);
  margin-bottom: var(--space-1);
}

/* =============================================
   相关文章行
   ============================================= */
.cards-row {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: var(--space-3);
}

/* =============================================
   Legal 页专属
   ============================================= */
.page-main--legal .wrap {
  max-width: 720px;
}

.legal-hero {
  padding: var(--space-7) 0 var(--space-4);
}

.legal-date {
  font-size: 0.875rem;
  color: var(--c-gray-400);
  margin-top: var(--space-2);
}

/* =============================================
   子页面 time 标签
   ============================================= */
time {
  font-variant-numeric: tabular-nums;
}

/* =============================================
   页脚
   ============================================= */
.site-footer {
  background: var(--c-black);
  color: var(--c-white);
  margin-left: var(--nav-width);
  padding: var(--space-6) var(--space-4) var(--space-3);
}

.footer-inner {
  max-width: 960px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  gap: var(--space-5);
  padding-bottom: var(--space-5);
  border-bottom: 1px solid rgba(255,255,255,0.12);
}

.footer-col dt {
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: rgba(255,255,255,0.5);
  margin-bottom: var(--space-2);
}

.footer-col dd {
  margin-bottom: var(--space-1);
}

.footer-brand-name {
  font-size: 1rem;
  font-weight: 700;
  color: var(--c-white);
  margin-bottom: var(--space-2);
  display: block;
}

.footer-brand-desc {
  font-size: 0.875rem;
  color: rgba(255,255,255,0.6);
  line-height: 1.55;
  margin-bottom: var(--space-3);
}

.footer-link {
  font-size: 0.875rem;
  color: rgba(255,255,255,0.7);
  transition: color var(--transition-fast);
  display: inline-block;
  min-height: 28px;
  line-height: 28px;
}

.footer-link:hover {
  color: var(--c-white);
  text-decoration: none;
}

.footer-bottom {
  max-width: 960px;
  margin: var(--space-3) auto 0;
  font-size: 0.75rem;
  color: rgba(255,255,255,0.35);
}

/* =============================================
   空态提示
   ============================================= */
.empty-tip {
  color: var(--c-gray-400);
  font-size: 0.875rem;
  padding: var(--space-3) 0;
}

/* =============================================
   Parallax scroll 动效（纯 CSS）
   ============================================= */
@supports (animation-timeline: scroll()) {
  @media (prefers-reduced-motion: no-preference) {
    .hero-grid-decoration .grid-pattern {
      animation: parallaxDown linear both;
      animation-timeline: scroll(root);
      animation-range: 0vh 50vh;
    }

    @keyframes parallaxDown {
      from { transform: translateY(0); }
      to   { transform: translateY(32px); }
    }
  }
}

/* =============================================
   移动端响应式
   ============================================= */
@media (max-width: 1024px) {
  :root {
    --nav-width: 200px;
  }
}

@media (max-width: 768px) {
  :root {
    --nav-width: 0px;
  }

  .page-shell {
    flex-direction: column;
  }

  .site-header {
    position: sticky;
    top: 0;
    width: 100%;
    height: auto;
    flex-direction: column;
    overflow: visible;
    z-index: 200;
  }

  .site-header__brand {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--space-2) var(--space-3);
  }

  .site-header__tagline {
    display: none;
  }

  .site-nav {
    flex-direction: row;
    flex-wrap: wrap;
    padding: var(--space-1) var(--space-2);
    gap: 4px;
    border-top: 1px solid rgba(255,255,255,0.12);
    overflow-x: auto;
  }

  .nav-link {
    border-left: none;
    border-bottom: 2px solid transparent;
    padding: 10px var(--space-2);
    font-size: 0.75rem;
    white-space: nowrap;
    min-height: 40px;
    flex-shrink: 0;
  }

  .nav-link--active {
    border-bottom-color: var(--c-white);
    border-left-color: transparent;
  }

  .page-main {
    margin-left: 0;
  }

  .site-footer {
    margin-left: 0;
  }

  .footer-inner {
    grid-template-columns: 1fr;
    gap: var(--space-4);
  }

  .hero-section {
    grid-template-columns: 1fr;
    min-height: auto;
    padding: var(--space-5) 0;
  }

  .hero-grid-decoration {
    display: none;
  }

  .hero-title {
    font-size: 1.875rem;
  }

  .about-hero {
    grid-template-columns: 1fr;
  }

  .about-decoration {
    display: none;
  }

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

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

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

  .wrap {
    padding: 0 var(--space-3);
  }

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

  .card--list .card-media {
    width: 100%;
    max-height: 160px;
  }

  .card--list .card-thumb {
    width: 100%;
    height: 160px;
  }
}

@media (max-width: 480px) {
  .topic-grid {
    grid-template-columns: 1fr;
  }

  .page-h1 {
    font-size: 1.5rem;
  }

  .article-title {
    font-size: 1.5rem;
  }

  .cta-block {
    flex-direction: column;
    align-items: flex-start;
  }

  .nav-hint-links {
    flex-direction: column;
    align-items: flex-start;
  }
}