/* roulang page: index */
/* CSS 变量与设计系统 */
    :root {
      --primary: #1A1A2E;
      --secondary: #D4A853;
      --accent: #3A6B5C;
      --bg-light: #F8F6F2;
      --bg-card: #FFFFFF;
      --bg-dark: #1A1A2E;
      --text-primary: #1A1A2E;
      --text-body: #3D3D3D;
      --text-muted: #6B6B6B;
      --text-on-dark: #FFFFFF;
      --text-gold: #D4A853;
      --border-light: #E5E0D8;
      --shadow-card: 0 8px 30px rgba(26,26,46,0.08);
      --shadow-card-hover: 0 12px 40px rgba(26,26,46,0.12);
      --shadow-btn: 0 4px 14px rgba(212,168,83,0.35);
      --radius-card: 16px;
      --radius-btn: 10px;
      --radius-badge: 20px;
      --font-sans: "PingFang SC", "Microsoft YaHei", "Hiragino Sans GB", "Noto Sans SC", system-ui, -apple-system, sans-serif;
      --font-number: "Inter", "SF Pro Display", system-ui, sans-serif;
      --nav-width: 240px;
      --topbar-height: 56px;
    }
    * { box-sizing: border-box; margin: 0; padding: 0; }
    body {
      font-family: var(--font-sans);
      background-color: var(--bg-light);
      color: var(--text-body);
      line-height: 1.7;
      -webkit-font-smoothing: antialiased;
      display: flex;
      min-height: 100vh;
    }
    img { max-width: 100%; height: auto; display: block; }
    a { text-decoration: none; color: inherit; transition: all 0.25s ease; }
    button, input, textarea { font-family: inherit; }

    /* 左侧导航桌面固定 */
    .app-nav {
      position: fixed;
      left: 0;
      top: 0;
      width: var(--nav-width);
      height: 100vh;
      background-color: var(--primary);
      color: white;
      display: flex;
      flex-direction: column;
      z-index: 50;
      transition: transform 0.3s ease;
      border-right: 1px solid rgba(255,255,255,0.08);
    }
    .nav-logo {
      height: 80px;
      display: flex;
      align-items: center;
      padding: 0 24px;
      gap: 12px;
      border-bottom: 1px solid rgba(255,255,255,0.08);
    }
    .logo-icon {
      width: 36px;
      height: 36px;
      background: var(--secondary);
      border-radius: 8px;
      display: flex;
      align-items: center;
      justify-content: center;
      font-weight: 700;
      font-size: 20px;
      color: var(--primary);
      flex-shrink: 0;
    }
    .nav-links {
      flex: 1;
      padding: 24px 16px;
      display: flex;
      flex-direction: column;
      gap: 8px;
    }
    .nav-item {
      display: flex;
      align-items: center;
      padding: 12px 16px;
      border-radius: 10px;
      font-size: 15px;
      font-weight: 500;
      color: rgba(255,255,255,0.75);
      transition: all 0.2s ease;
      position: relative;
    }
    .nav-item:hover, .nav-item.active {
      color: white;
      background: rgba(255,255,255,0.06);
    }
    .nav-item.active::before {
      content: '';
      position: absolute;
      left: 0;
      top: 12px;
      bottom: 12px;
      width: 4px;
      background: var(--secondary);
      border-radius: 0 4px 4px 0;
    }
    .nav-footer {
      padding: 20px 24px;
      border-top: 1px solid rgba(255,255,255,0.08);
    }
    .btn-nav-contact {
      display: block;
      width: 100%;
      text-align: center;
      padding: 10px 18px;
      border: 1.5px solid var(--secondary);
      color: var(--secondary);
      border-radius: var(--radius-btn);
      font-weight: 600;
      background: transparent;
      cursor: pointer;
      transition: all 0.25s;
    }
    .btn-nav-contact:hover {
      background: var(--secondary);
      color: var(--primary);
    }

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

    /* 移动端顶部栏 */
    .mobile-topbar {
      display: none;
      position: fixed;
      top: 0;
      left: 0;
      right: 0;
      height: var(--topbar-height);
      background: var(--primary);
      color: white;
      align-items: center;
      padding: 0 20px;
      z-index: 55;
      justify-content: space-between;
    }
    .hamburger {
      background: none;
      border: none;
      color: white;
      font-size: 24px;
      cursor: pointer;
      padding: 8px;
    }
    .mobile-logo {
      font-weight: 700;
      font-size: 18px;
      display: flex;
      align-items: center;
      gap: 8px;
    }
    .drawer-overlay {
      position: fixed;
      inset: 0;
      background: rgba(0,0,0,0.5);
      z-index: 60;
      display: none;
    }
    .drawer-overlay.open {
      display: block;
    }

    /* 抽屉 */
    .mobile-drawer {
      position: fixed;
      left: 0;
      top: 0;
      bottom: 0;
      width: 280px;
      background: var(--primary);
      z-index: 70;
      transform: translateX(-100%);
      transition: transform 0.3s ease;
      display: flex;
      flex-direction: column;
    }
    .mobile-drawer.open {
      transform: translateX(0);
    }
    .drawer-close {
      position: absolute;
      top: 16px;
      right: 16px;
      background: none;
      border: none;
      color: white;
      font-size: 24px;
      cursor: pointer;
    }

    /* 通用区块间距 */
    section {
      padding: 100px 40px;
    }
    .section-title {
      font-size: 36px;
      font-weight: 600;
      line-height: 1.25;
      color: var(--text-primary);
      margin-bottom: 16px;
      position: relative;
      display: inline-block;
    }
    .section-title::after {
      content: '';
      position: absolute;
      left: 0;
      bottom: -8px;
      width: 60px;
      height: 4px;
      background: var(--secondary);
      border-radius: 2px;
    }
    .section-subtitle {
      font-size: 16px;
      color: var(--text-muted);
      margin-bottom: 48px;
    }

    /* 卡片通用 */
    .card {
      background: var(--bg-card);
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-card);
      transition: all 0.3s ease;
    }
    .card:hover {
      box-shadow: var(--shadow-card-hover);
      transform: translateY(-4px);
    }

    /* 按钮 */
    .btn-primary {
      background: linear-gradient(135deg, #D4A853 0%, #B8913A 100%);
      color: white;
      font-weight: 600;
      padding: 14px 32px;
      border-radius: var(--radius-btn);
      border: none;
      cursor: pointer;
      box-shadow: var(--shadow-btn);
      transition: all 0.3s ease;
      display: inline-flex;
      align-items: center;
      gap: 8px;
    }
    .btn-primary:hover {
      filter: brightness(1.1);
      transform: translateY(-2px);
      box-shadow: 0 8px 24px rgba(212,168,83,0.45);
    }

    /* 响应式 */
    @media (max-width: 1024px) {
      .app-nav { display: none; }
      .main-content { margin-left: 0; }
      .mobile-topbar { display: flex; }
      section { padding: 70px 24px; }
      .section-title { font-size: 30px; }
    }
    @media (max-width: 768px) {
      section { padding: 50px 20px; }
      .section-title { font-size: 28px; }
    }