/* roulang page: index */
:root {
      --racing-red: #C41E3A;
      --charcoal: #1E1E1E;
      --champagne: #D4AF37;
      --warm-gray: #F5F3F0;
      --soft-white: #FFFFFF;
      --text-primary: #1A1A1A;
      --text-secondary: #5C5C5C;
      --text-reverse: #FAFAFA;
      --shadow-card: 0 4px 20px rgba(0,0,0,0.06);
      --shadow-hover: 0 8px 30px rgba(0,0,0,0.12);
      --radius-card: 12px;
      --radius-btn: 8px;
      --transition-base: 0.3s ease;
      --transition-btn: 0.2s ease;
      --max-width-content: 1120px;
      --nav-width: 220px;
    }
    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }
    body {
      font-family: 'Inter', system-ui, -apple-system, 'Segoe UI', Roboto, sans-serif;
      background-color: var(--warm-gray);
      color: var(--text-primary);
      line-height: 1.75;
      overflow-x: hidden;
    }
    img {
      max-width: 100%;
      height: auto;
      display: block;
    }
    a {
      text-decoration: none;
      color: inherit;
      transition: color var(--transition-base);
    }
    button, .btn {
      cursor: pointer;
      transition: all var(--transition-btn);
      font-family: inherit;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
      border: none;
      outline: none;
    }
    .container-main {
      margin-left: var(--nav-width);
      max-width: 100%;
    }
    .content-grid {
      max-width: var(--max-width-content);
      margin-left: auto;
      margin-right: auto;
      padding-left: 2rem;
      padding-right: 2rem;
    }
    .section-spacing {
      padding-top: 5rem;
      padding-bottom: 5rem;
    }
    .text-serif {
      font-family: 'Noto Serif SC', 'Songti SC', 'SimSun', serif;
    }
    /* 左侧导航 */
    .side-nav {
      position: fixed;
      left: 0;
      top: 0;
      width: var(--nav-width);
      height: 100vh;
      background-color: var(--charcoal);
      color: var(--text-reverse);
      display: flex;
      flex-direction: column;
      z-index: 50;
      box-shadow: var(--shadow-nav);
      transition: transform 0.3s ease;
    }
    .nav-brand {
      padding: 2rem 1.5rem 1.5rem;
      border-bottom: 1px solid rgba(212,175,55,0.2);
      margin-bottom: 1.5rem;
    }
    .nav-logo {
      font-size: 1.5rem;
      font-weight: 700;
      letter-spacing: 1px;
      color: var(--soft-white);
      display: flex;
      align-items: center;
      gap: 0.5rem;
    }
    .nav-logo span {
      color: var(--champagne);
    }
    .nav-links {
      flex: 1;
      display: flex;
      flex-direction: column;
      padding: 0 0.75rem;
      gap: 0.25rem;
    }
    .nav-link {
      padding: 0.8rem 1rem;
      border-radius: 6px;
      color: #ccc;
      font-weight: 500;
      transition: all 0.2s;
      border-left: 3px solid transparent;
      display: block;
    }
    .nav-link:hover, .nav-link.active {
      background-color: rgba(196,30,58,0.15);
      color: white;
      border-left-color: var(--racing-red);
    }
    .nav-footer {
      padding: 1.5rem;
      border-top: 1px solid rgba(255,255,255,0.1);
      font-size: 0.85rem;
      display: flex;
      justify-content: center;
      gap: 1.25rem;
    }
    .nav-footer a {
      color: #aaa;
      font-size: 1.2rem;
    }
    .nav-footer a:hover {
      color: var(--racing-red);
    }
    /* 移动端顶部导航 */
    .mobile-header {
      display: none;
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      background-color: var(--charcoal);
      color: white;
      z-index: 55;
      padding: 0.75rem 1.5rem;
      align-items: center;
      justify-content: space-between;
    }
    .hamburger {
      font-size: 1.8rem;
      background: none;
      border: none;
      color: white;
    }
    .mobile-menu {
      display: none;
      position: fixed;
      top: 60px;
      left: 0;
      width: 100%;
      background-color: var(--charcoal);
      flex-direction: column;
      padding: 1rem 2rem;
      z-index: 54;
      gap: 0.5rem;
    }
    .mobile-menu a {
      color: #ddd;
      padding: 0.75rem 0;
      border-bottom: 1px solid rgba(255,255,255,0.1);
    }
    /* 卡片与组件 */
    .card-hover {
      transition: all var(--transition-base);
    }
    .card-hover:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-hover);
    }
    .btn-primary {
      background-color: var(--racing-red);
      color: white;
      padding: 0.85rem 2.2rem;
      border-radius: var(--radius-btn);
      font-weight: 600;
    }
    .btn-primary:hover {
      background-color: #A01830;
    }
    .btn-outline {
      border: 2px solid var(--racing-red);
      color: var(--racing-red);
      background: transparent;
      padding: 0.75rem 2rem;
      border-radius: var(--radius-btn);
      font-weight: 600;
    }
    .btn-outline:hover {
      background-color: rgba(196,30,58,0.08);
    }
    .accent-dot {
      width: 8px;
      height: 8px;
      background-color: var(--racing-red);
      border-radius: 50%;
      display: inline-block;
    }
    .champagne-line {
      height: 2px;
      background-color: var(--champagne);
      width: 60px;
    }
    /* FAQ 手风琴 */
    .faq-item {
      border-bottom: 1px solid #e2e0dc;
      padding: 1.2rem 0;
      cursor: pointer;
    }
    .faq-question {
      display: flex;
      align-items: center;
      gap: 0.75rem;
      font-weight: 600;
      color: var(--text-primary);
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.35s ease;
      color: var(--text-secondary);
      padding-left: 1.8rem;
    }
    .faq-item.active .faq-answer {
      max-height: 200px;
    }
    /* 横向滚动案例 */
    .scroll-container {
      display: flex;
      gap: 1.5rem;
      overflow-x: auto;
      padding-bottom: 1rem;
      scroll-snap-type: x mandatory;
    }
    .scroll-card {
      min-width: 280px;
      background: white;
      border-radius: var(--radius-card);
      padding: 1.8rem;
      box-shadow: var(--shadow-card);
      scroll-snap-align: start;
    }
    /* 响应式 */
    @media (max-width: 1024px) {
      .container-main {
        margin-left: 0;
      }
      .side-nav {
        transform: translateX(-100%);
      }
      .mobile-header {
        display: flex;
      }
      .mobile-menu.open {
        display: flex;
      }
      .content-grid {
        padding-left: 1.5rem;
        padding-right: 1.5rem;
      }
    }
    @media (max-width: 768px) {
      .section-spacing {
        padding-top: 3.5rem;
        padding-bottom: 3.5rem;
      }
      h1 {
        font-size: 2.4rem !important;
      }
      h2 {
        font-size: 2rem !important;
      }
    }