:root {
    --bg: #F7F5F2;
    --bg-alt: #EFECE6;
    --surface: #FFFFFF;
    --ink: #1E1C1A;
    --ink-2: #5C5852;
    --ink-3: #99938A;
    --brand: #C9372C;
    --brand-soft: #F7E8E6;
    --line: #E2DDD5;
  }
  * { box-sizing: border-box; margin: 0; padding: 0; }
  html { scroll-behavior: smooth; }
  body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    background-color: var(--bg);
    color: var(--ink);
    line-height: 1.8;
    font-size: 15px;
    -webkit-font-smoothing: antialiased;
    overflow-x: hidden;
  }
  a { text-decoration: none; color: inherit; }
  ul { list-style: none; }
  img { max-width: 100%; display: block; }
  
  .container { max-width: 1080px; margin: 0 auto; padding: 0 20px; }
  .section-space { margin-bottom: 88px; }
  
  /* 00 服务条 */
  .service-bar {
    background-color: var(--ink);
    color: rgba(255, 255, 255, 0.84);
    font-size: 12.5px;
    text-align: center;
    height: 36px;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 0 16px;
  }
  .age-badge {
    font-size: 11px;
    color: #fff;
    border: 1px solid rgba(255,255,255,0.4);
    border-radius: 4px;
    padding: 0 4px;
    line-height: 1.4;
    display: inline-block;
    vertical-align: middle;
  }

  /* 01 导航 */
  .nav-header {
    position: sticky;
    top: 0;
    z-index: 100;
    background-color: rgba(247, 245, 242, 0.85);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--line);
  }
  .nav-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 64px;
  }
  .brand {
    display: flex;
    align-items: center;
    gap: 10px;
    font-weight: 800;
    font-size: 18px;
    color: var(--ink);
  }
  .brand img { height: 32px; width: auto; }
  .nav-links {
    display: flex;
    gap: 24px;
  }
  .nav-links a {
    font-size: 14px;
    font-weight: 500;
    color: var(--ink-2);
    transition: color 0.2s;
  }
  .nav-links a:hover { color: var(--brand); }
  .btn-primary {
    background-color: var(--brand);
    color: #fff;
    padding: 8px 20px;
    border-radius: 999px;
    font-size: 14px;
    font-weight: 600;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    transition: opacity 0.2s;
  }
  .btn-primary:hover { opacity: 0.9; }
  .mobile-menu-btn { display: none; }

  /* 02 首屏 */
  .hero {
    display: grid;
    grid-template-columns: 1.05fr 1fr;
    gap: 48px;
    align-items: center;
    padding-top: 48px;
  }
  .hero-content { max-width: 480px; }
  .hero-tag {
    font-size: 12px;
    text-transform: uppercase;
    letter-spacing: 0.2em;
    color: var(--ink-3);
    margin-bottom: 16px;
    font-weight: 600;
  }
  .hero h1 {
    font-size: clamp(36px, 5vw, 58px);
    font-weight: 800;
    line-height: 1.15;
    margin-bottom: 20px;
    letter-spacing: -0.02em;
  }
  .hero-claim {
    font-size: 20px;
    font-weight: 500;
    font-style: italic;
    color: var(--ink-2);
    margin-bottom: 16px;
  }
  .hero-desc {
    font-size: 15px;
    line-height: 1.85;
    color: var(--ink-2);
    margin-bottom: 32px;
  }
  .hero-actions {
    display: flex;
    gap: 12px;
    margin-bottom: 32px;
  }
  .btn-outline {
    border: 1px solid var(--line);
    background-color: var(--surface);
    color: var(--ink);
    padding: 8px 20px;
    border-radius: 999px;
    font-size: 14px;
    font-weight: 600;
    transition: border-color 0.2s;
  }
  .btn-outline:hover { border-color: var(--brand); }
  .hero-pills {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 10px;
    max-width: 320px;
  }
  .pill {
    border: 1px solid var(--line);
    border-radius: 999px;
    padding: 6px 14px;
    font-size: 12px;
    color: var(--ink-2);
    text-align: center;
  }
  .stack {
    position: relative;
    width: 100%;
    aspect-ratio: 4/3;
    margin-top: 40px;
  }
  .stack-img-main {
    width: 64%;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    z-index: 2;
    border-radius: 12px;
    border: 1px solid #fff;
    box-shadow: 0 10px 30px rgba(0,0,0,0.1);
    aspect-ratio: 3/4;
    object-fit: cover;
    object-position: 50% 22%;
  }
  .stack-img-a {
    width: 32%;
    position: absolute;
    top: -5%;
    left: 0;
    transform: rotate(-3deg);
    z-index: 1;
    border-radius: 8px;
    border: 1px solid #fff;
    box-shadow: 0 8px 20px rgba(0,0,0,0.08);
    aspect-ratio: 3/4;
    object-fit: cover;
    object-position: 50% 22%;
  }
  .stack-img-b {
    width: 32%;
    position: absolute;
    bottom: -5%;
    right: 0;
    transform: rotate(3deg);
    z-index: 3;
    border-radius: 8px;
    border: 1px solid #fff;
    box-shadow: 0 8px 20px rgba(0,0,0,0.08);
    aspect-ratio: 3/4;
    object-fit: cover;
    object-position: 50% 22%;
  }
  .img-overlay {
    position: relative;
  }
  .img-overlay::after {
    content: '';
    position: absolute;
    inset: 0;
    background: linear-gradient(180deg, transparent 42%, rgba(0,0,0,.5));
    border-radius: inherit;
    pointer-events: none;
  }

  /* 03 双引擎 */
  .engine-section {
    display: grid;
    grid-template-columns: 1fr 1fr;
    background-color: var(--bg-alt);
    border-radius: 20px;
    padding: 32px;
    position: relative;
  }
  .engine-section::before {
    content: '';
    position: absolute;
    top: 32px;
    bottom: 32px;
    left: 50%;
    border-left: 1px dashed var(--line);
    transform: translateX(-50%);
  }
  .engine-col { padding: 0 24px; }
  .engine-col:first-child { padding-left: 0; }
  .engine-col:last-child { padding-right: 0; }
  .engine-slogan {
    font-size: 16px;
    font-weight: 600;
    margin-bottom: 20px;
    color: var(--ink);
  }
  .engine-item { margin-bottom: 16px; }
  .engine-label {
    font-size: 12px;
    font-weight: 600;
    color: var(--brand);
    margin-bottom: 4px;
    display: block;
  }
  .engine-text {
    font-size: 14px;
    color: var(--ink-2);
    line-height: 1.6;
  }

  /* 04 内容线入口 */
  .entry-cards {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 20px;
  }
  .entry-card {
    background-color: var(--surface);
    border: 1px solid var(--line);
    border-radius: 16px;
    padding: 24px;
    display: flex;
    flex-direction: column;
    transition: transform 0.2s, border-color 0.2s;
    height: 100%;
  }
  .entry-card:hover {
    transform: translateY(-2px);
    border-color: var(--brand);
  }
  .entry-icon {
    font-size: 24px;
    margin-bottom: 16px;
    display: flex;
    align-items: center;
    height: 24px;
  }
  .entry-title {
    font-size: 18px;
    font-weight: 600;
    margin-bottom: 8px;
  }
  .entry-for {
    font-size: 13px;
    color: var(--ink-3);
    margin-bottom: 24px;
    flex-grow: 1;
  }
  .entry-link {
    font-size: 13px;
    font-weight: 600;
    color: var(--brand);
    display: flex;
    align-items: center;
    gap: 4px;
  }

  /* 05 题材墙 */
  .genre-wall {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    border: 1px solid var(--line);
    border-radius: 0;
  }
  .genre-cell {
    padding: 22px;
    border-right: 1px solid var(--line);
    border-bottom: 1px solid var(--line);
    display: flex;
    justify-content: space-between;
    align-items: flex-end;
    transition: background-color 0.2s;
    cursor: pointer;
    min-height: 90px;
  }
  .genre-cell:nth-child(4n) { border-right: none; }
  .genre-cell:nth-last-child(-n+4) { border-bottom: none; }
  .genre-cell:hover { background-color: var(--brand-soft); }
  .genre-name { font-size: 15px; font-weight: 600; color: var(--ink); }
  .genre-arrow { font-size: 14px; color: var(--ink-3); }

  /* 06 排名轨道 */
  .section-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-end;
    margin-bottom: 24px;
  }
  .section-title {
    font-size: 24px;
    font-weight: 700;
    letter-spacing: -0.01em;
  }
  .section-link {
    font-size: 14px;
    font-weight: 600;
    color: var(--brand);
  }
  .rank-track {
    display: flex;
    gap: 20px;
  }
  .rank-item { flex: 1; display: flex; flex-direction: column; }
  .rank-num {
    font-size: 40px;
    font-weight: 800;
    color: var(--brand);
    opacity: 0.9;
    font-variant-numeric: tabular-nums;
    line-height: 1;
    margin-bottom: 8px;
  }
  .rank-cover-wrap {
    width: 100%;
    aspect-ratio: 3/4;
    border-radius: 10px;
    overflow: hidden;
    margin-bottom: 12px;
    background-color: var(--bg-alt);
  }
  .rank-cover-wrap img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    object-position: 50% 22%;
  }
  .rank-title {
    font-size: 13.5px;
    font-weight: 600;
    line-height: 1.4;
    margin-bottom: 4px;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
  }
  .rank-ep {
    font-size: 12px;
    color: var(--ink-2);
  }

  /* 07 专题片单 */
  .playlist-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 20px;
  }
  .playlist-card {
    display: block;
    transition: transform 0.2s;
  }
  .playlist-card:hover { transform: translateY(-2px); }
  .playlist-cover {
    width: 100%;
    aspect-ratio: 3/4;
    border-radius: 12px;
    overflow: hidden;
    margin-bottom: 12px;
    background-color: var(--bg-alt);
  }
  .playlist-cover img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    object-position: 50% 22%;
  }
  .playlist-tag {
    font-size: 12px;
    text-transform: uppercase;
    letter-spacing: 0.14em;
    color: var(--brand);
    font-weight: 600;
    margin-bottom: 4px;
    display: block;
  }
  .playlist-name {
    font-size: 20px;
    font-weight: 700;
    margin-bottom: 4px;
    color: var(--ink);
    line-height: 1.3;
  }
  .playlist-for {
    font-size: 12.5px;
    color: var(--ink-2);
  }

  /* 08 安装区 */
  .install-section {
    background-color: var(--bg-alt);
    border-radius: 24px;
    padding: 56px;
    text-align: center;
    display: flex;
    flex-direction: column;
    align-items: center;
  }
  .install-title {
    font-size: 28px;
    font-weight: 700;
    line-height: 1.4;
    margin-bottom: 16px;
  }
  .install-desc {
    font-size: 15px;
    color: var(--ink-2);
    margin-bottom: 32px;
    max-width: 400px;
    line-height: 1.6;
  }
  .install-actions {
    display: flex;
    align-items: center;
    gap: 24px;
    margin-bottom: 32px;
  }
  .btn-large {
    background-color: var(--surface);
    color: var(--ink);
    height: 48px;
    padding: 0 32px;
    border-radius: 999px;
    font-size: 16px;
    font-weight: 600;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 0 4px 12px rgba(0,0,0,0.05);
    transition: transform 0.2s;
  }
  .btn-large:hover { transform: translateY(-1px); }
  .qr-box {
    width: 120px;
    height: 120px;
    background-color: var(--surface);
    border: 1px solid var(--line);
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 8px;
  }
  .qr-box img { width: 100%; height: 100%; object-fit: contain; }
  .version-info { font-size: 12px; color: var(--ink-3); }

  /* 09 答疑区 */
  .faq-list {
    border-top: 1px solid var(--line);
  }
  .faq-item {
    border-bottom: 1px solid var(--line);
  }
  .faq-item summary {
    list-style: none;
    display: flex;
    align-items: center;
    padding: 20px 0;
    cursor: pointer;
    outline: none;
  }
  .faq-item summary::-webkit-details-marker { display: none; }
  .faq-num {
    font-size: 12px;
    color: var(--ink-3);
    font-variant-numeric: tabular-nums;
    width: 36px;
    flex-shrink: 0;
  }
  .faq-q {
    font-size: 15px;
    font-weight: 600;
    flex-grow: 1;
  }
  .faq-icon {
    position: relative;
    width: 22px;
    height: 22px;
    flex-shrink: 0;
  }
  .faq-icon::before,
  .faq-icon::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    background-color: var(--ink-2);
    transition: transform 0.2s, opacity 0.2s;
  }
  .faq-icon::before { width: 12px; height: 1.5px; transform: translate(-50%, -50%); }
  .faq-icon::after { width: 1.5px; height: 12px; transform: translate(-50%, -50%); }
  .faq-item[open] .faq-icon::after { transform: translate(-50%, -50%) rotate(90deg); opacity: 0; }
  .faq-answer {
    padding-left: 36px;
    padding-bottom: 20px;
    font-size: 13.5px;
    line-height: 1.85;
    color: var(--ink-2);
  }

  /* 10 页脚 */
  .site-footer {
    border-top: 1px solid var(--line);
    padding-top: 48px;
    padding-bottom: 96px;
    font-size: 14px;
  }
  .footer-top {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 40px;
  }
  .footer-brand {
    font-size: 18px;
    font-weight: 800;
    margin-bottom: 8px;
  }
  .footer-slogan {
    font-size: 13px;
    color: var(--ink-2);
    max-width: 400px;
  }
  .footer-back {
    font-weight: 600;
    color: var(--ink-2);
    transition: color 0.2s;
  }
  .footer-back:hover { color: var(--brand); }
  .footer-links {
    display: flex;
    flex-direction: column;
    gap: 12px;
    margin-bottom: 24px;
  }
  .footer-links-row {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    color: var(--ink-2);
  }
  .footer-links-row a:hover { color: var(--ink); }
  .dot { margin: 0 12px; color: var(--line); }
  .footer-bottom {
    font-size: 12px;
    color: var(--ink-3);
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
  }

  /* 移动端吸底条 */
  .sticky-bar {
    display: none;
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    background-color: var(--surface);
    border-top: 1px solid var(--line);
    padding: 12px 20px;
    padding-bottom: calc(12px + env(safe-area-inset-bottom));
    z-index: 999;
    align-items: center;
    justify-content: space-between;
    transition: opacity 0.3s, transform 0.3s;
  }
  .sticky-bar.hidden {
    opacity: 0;
    transform: translateY(100%);
    pointer-events: none;
  }
  .sticky-text { font-size: 13px; font-weight: 500; color: var(--ink-2); }

  /* 响应式 */
  @media (max-width: 1024px) {
    .hero { gap: 32px; }
    .hero h1 { font-size: 42px; }
    .rank-track { flex-wrap: wrap; }
    .rank-item { flex: 0 0 calc(20% - 16px); }
    .playlist-grid { grid-template-columns: repeat(2, 1fr); }
  }

  @media (max-width: 900px) {
    .hero { grid-template-columns: 1fr; text-align: left; padding-top: 24px; }
    .hero-content { max-width: 100%; }
    .hero-actions { flex-wrap: wrap; }
    .hero-pills { max-width: 100%; }
    .stack { aspect-ratio: 3/4; max-width: 360px; margin: 0 auto; }
    .stack-img-a, .stack-img-b { display: none; }
    .stack-img-main { width: 100%; border-radius: 16px; }
    .engine-section { grid-template-columns: 1fr; gap: 32px; padding: 24px; }
    .engine-section::before { display: none; }
    .engine-section { border-top: 1px dashed var(--line); margin-top: 32px; padding-top: 32px; }
    .engine-col { padding: 0; }
    .entry-cards { grid-template-columns: 1fr; }
    .genre-wall { grid-template-columns: repeat(2, 1fr); }
    .genre-cell { border-right: 1px solid var(--line); border-bottom: 1px solid var(--line); }
    .genre-cell:nth-child(2n) { border-right: none; }
    .genre-cell:nth-last-child(-n+2) { border-bottom: none; }
    .rank-track {
      overflow-x: auto;
      scroll-snap-type: x mandatory;
      padding-bottom: 16px;
      -webkit-overflow-scrolling: touch;
      margin-right: -20px;
      padding-right: 20px;
    }
    .rank-item { flex: 0 0 44vw; scroll-snap-align: start; }
    .playlist-grid {
      display: flex;
      overflow-x: auto;
      scroll-snap-type: x mandatory;
      gap: 16px;
      padding-bottom: 16px;
      margin-right: -20px;
      padding-right: 20px;
      -webkit-overflow-scrolling: touch;
    }
    .playlist-card { flex: 0 0 62vw; scroll-snap-align: start; }
    .install-section { padding: 40px 24px; }
    .install-actions { flex-direction: column; gap: 20px; }
    .footer-top { flex-direction: column; gap: 24px; }
    .site-footer { padding-bottom: 100px; }
  }

  @media (max-width: 768px) {
    .section-space { margin-bottom: 52px; }
    .nav-links { display: none; }
    .nav-links.active { 
      display: flex; 
      flex-direction: column; 
      position: absolute; 
      top: 64px; 
      left: 0; 
      right: 0; 
      background-color: var(--bg); 
      padding: 20px; 
      border-bottom: 1px solid var(--line);
      gap: 16px;
    }
    .mobile-menu-btn {
      display: block;
      font-size: 20px;
      margin-left: 16px;
      cursor: pointer;
      background: none;
      border: none;
      color: var(--ink);
    }
    .nav-inner { justify-content: flex-start; }
    .nav-right { margin-left: auto; display: flex; align-items: center; }
    .sticky-bar { display: flex; }
    .hero-pills { grid-template-columns: 1fr; }
    .hero-pills .pill:last-child { grid-column: span 1; }
  }

  @media (max-width: 560px) {
    .hero h1 { font-size: 32px; }
    .hero-claim { font-size: 18px; }
    .genre-wall { grid-template-columns: repeat(2, 1fr); }
    .faq-answer { padding-left: 0; }
    .install-title { font-size: 24px; }
  }