/* roulang page: index */
/* ----- 设计变量 & 基础重置 ----- */
    :root {
      --primary: #00F0FF;
      --primary-glow: rgba(0, 240, 255, 0.5);
      --secondary: #FF4D6D;
      --bg-dark: #0A0E27;
      --bg-card: rgba(26, 31, 58, 0.6);
      --bg-card-hover: #1A1F3A;
      --text-primary: #FFFFFF;
      --text-secondary: #B0B8D0;
      --border-light: #2A2F4A;
      --border-primary-glow: rgba(0, 240, 255, 0.15);
      --radius-lg: 16px;
      --radius-md: 12px;
      --radius-sm: 8px;
      --shadow-card: 0 8px 32px rgba(0, 0, 0, 0.4);
      --shadow-glow: 0 0 20px var(--primary-glow);
      --font-sans: "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
      --font-mono: "Inter", "SF Mono", "Courier New", monospace;
      --max-width: 1280px;
      --section-gap: 80px;
    }
    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }
    html {
      scroll-behavior: smooth;
      font-size: 16px;
    }
    body {
      font-family: var(--font-sans);
      background-color: var(--bg-dark);
      color: var(--text-primary);
      line-height: 1.6;
      -webkit-font-smoothing: antialiased;
      background-image: 
        linear-gradient(rgba(0, 240, 255, 0.02) 1px, transparent 1px),
        linear-gradient(90deg, rgba(0, 240, 255, 0.02) 1px, transparent 1px);
      background-size: 40px 40px;
    }
    .container {
      max-width: var(--max-width);
      margin: 0 auto;
      padding: 0 24px;
    }
    a {
      text-decoration: none;
      color: inherit;
      transition: color 0.2s ease;
    }
    img {
      max-width: 100%;
      display: block;
    }
    button, input, textarea {
      font-family: inherit;
    }

    /* ----- 导航：频道Tabs双层结构 ----- */
    .site-header {
      position: sticky;
      top: 0;
      z-index: 100;
      background: rgba(10, 14, 39, 0.85);
      backdrop-filter: blur(16px);
      border-bottom: 1px solid var(--border-light);
      box-shadow: 0 4px 20px rgba(0,0,0,0.4);
    }
    .header-top {
      display: flex;
      align-items: center;
      justify-content: space-between;
      padding: 16px 0;
    }
    .logo {
      font-size: 28px;
      font-weight: 700;
      letter-spacing: 1px;
      color: var(--text-primary);
      text-shadow: 0 0 12px var(--primary-glow);
      display: flex;
      align-items: center;
      gap: 8px;
    }
    .logo i {
      color: var(--primary);
      font-size: 32px;
      filter: drop-shadow(0 0 8px var(--primary));
    }
    .header-actions {
      display: flex;
      align-items: center;
      gap: 20px;
    }
    .search-icon {
      font-size: 20px;
      color: var(--text-secondary);
      transition: color 0.2s;
      cursor: pointer;
    }
    .search-icon:hover {
      color: var(--primary);
    }
    .btn-primary {
      background: var(--primary);
      color: var(--bg-dark);
      font-weight: 600;
      padding: 10px 26px;
      border-radius: 30px;
      border: none;
      cursor: pointer;
      transition: all 0.25s ease;
      box-shadow: 0 0 15px var(--primary-glow);
      font-size: 15px;
      display: inline-flex;
      align-items: center;
      gap: 6px;
    }
    .btn-primary:hover {
      background: #33F5FF;
      box-shadow: 0 0 25px rgba(0,240,255,0.8);
      transform: translateY(-1px);
    }
    /* 第二行频道Tabs */
    .nav-tabs {
      display: flex;
      justify-content: center;
      gap: 8px;
      padding: 12px 0 16px;
      overflow-x: auto;
      white-space: nowrap;
      -webkit-overflow-scrolling: touch;
      scrollbar-width: thin;
    }
    .nav-tabs::-webkit-scrollbar {
      height: 4px;
    }
    .nav-tabs::-webkit-scrollbar-thumb {
      background: var(--primary);
      border-radius: 4px;
    }
    .tab-pill {
      background: rgba(26, 31, 58, 0.6);
      backdrop-filter: blur(8px);
      border: 1px solid var(--border-light);
      color: var(--text-secondary);
      padding: 8px 20px;
      border-radius: 24px;
      font-weight: 500;
      font-size: 15px;
      transition: all 0.2s ease;
      flex-shrink: 0;
    }
    .tab-pill:hover, .tab-pill.active {
      background: var(--primary);
      color: var(--bg-dark);
      border-color: var(--primary);
      box-shadow: 0 0 18px var(--primary-glow);
      font-weight: 600;
    }

    /* ----- 通用板块 ----- */
    section {
      padding: var(--section-gap) 0;
    }
    h2 {
      font-size: 36px;
      font-weight: 700;
      margin-bottom: 16px;
      letter-spacing: 0.5px;
      text-shadow: 0 2px 10px rgba(0,240,255,0.2);
    }
    .section-subtitle {
      color: var(--text-secondary);
      font-size: 18px;
      max-width: 700px;
      margin: 0 auto 48px;
      text-align: center;
    }

    /* Hero 双栏 */
    .hero-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 60px;
      align-items: center;
    }
    .hero-left h1 {
      font-size: 48px;
      font-weight: 700;
      line-height: 1.2;
      margin-bottom: 24px;
    }
    .hero-left h1 span {
      color: var(--primary);
      text-shadow: 0 0 20px var(--primary);
    }
    .hero-desc {
      font-size: 18px;
      color: var(--text-secondary);
      margin-bottom: 36px;
    }
    .hero-buttons {
      display: flex;
      gap: 20px;
      flex-wrap: wrap;
    }
    .btn-outline {
      background: transparent;
      border: 1.5px solid var(--primary);
      color: var(--primary);
      padding: 10px 26px;
      border-radius: 30px;
      font-weight: 600;
      transition: all 0.25s;
    }
    .btn-outline:hover {
      background: rgba(0,240,255,0.1);
      box-shadow: 0 0 18px var(--primary-glow);
    }
    .hero-right {
      display: flex;
      justify-content: center;
      align-items: center;
    }
    .hero-img {
      width: 100%;
      border-radius: var(--radius-lg);
      box-shadow: 0 20px 40px rgba(0,240,255,0.2);
      background: rgba(26,31,58,0.4);
      backdrop-filter: blur(4px);
    }

    /* 亮点网格 2x3 */
    .advantages-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
    }
    .adv-card {
      background: var(--bg-card);
      backdrop-filter: blur(12px);
      border: 1px solid var(--border-primary-glow);
      border-radius: var(--radius-lg);
      padding: 32px 24px;
      transition: all 0.3s;
    }
    .adv-card:hover {
      background: var(--bg-card-hover);
      box-shadow: var(--shadow-glow);
      transform: translateY(-6px);
    }
    .adv-icon {
      font-size: 36px;
      color: var(--primary);
      margin-bottom: 18px;
      filter: drop-shadow(0 0 8px var(--primary));
    }
    .adv-card h3 {
      font-size: 22px;
      margin-bottom: 12px;
    }
    .adv-card p {
      color: var(--text-secondary);
      font-size: 15px;
    }

    /* 案例瀑布流 (Masonry风格) */
    .cases-masonry {
      columns: 3;
      column-gap: 24px;
    }
    .case-item {
      break-inside: avoid;
      margin-bottom: 24px;
      border-radius: var(--radius-lg);
      overflow: hidden;
      position: relative;
      background: #1A1F3A;
      transition: transform 0.3s;
    }
    .case-item:hover {
      transform: scale(1.02);
    }
    .case-img {
      width: 100%;
      display: block;
      object-fit: cover;
    }
    .case-overlay {
      position: absolute;
      bottom: 0;
      left: 0;
      right: 0;
      background: linear-gradient(transparent, rgba(10,14,39,0.9));
      padding: 24px 16px;
      transition: 0.3s;
    }
    .case-item:hover .case-overlay {
      background: linear-gradient(transparent, rgba(0,240,255,0.3));
    }
    .case-tag {
      background: var(--secondary);
      color: white;
      font-size: 12px;
      padding: 4px 12px;
      border-radius: 16px;
      display: inline-block;
      margin-bottom: 8px;
    }
    .case-title {
      font-weight: 700;
      font-size: 20px;
    }

    /* 方案对比 */
    .compare-row {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 32px;
    }
    .compare-card {
      background: var(--bg-card);
      backdrop-filter: blur(12px);
      border-radius: var(--radius-lg);
      padding: 32px;
      border: 1px solid var(--border-light);
    }
    .compare-card.highlight {
      border: 1px solid var(--primary);
      box-shadow: 0 0 30px rgba(0,240,255,0.3);
    }
    .compare-list {
      list-style: none;
      margin-top: 20px;
    }
    .compare-list li {
      padding: 12px 0;
      border-bottom: 1px solid var(--border-light);
      display: flex;
      align-items: center;
      gap: 12px;
    }

    /* FAQ手风琴 */
    .faq-item {
      background: rgba(26,31,58,0.5);
      backdrop-filter: blur(8px);
      border: 1px solid var(--border-light);
      border-radius: var(--radius-md);
      margin-bottom: 16px;
      overflow: hidden;
    }
    .faq-question {
      padding: 20px 24px;
      font-weight: 700;
      display: flex;
      justify-content: space-between;
      align-items: center;
      cursor: pointer;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.4s ease;
      background: rgba(0,240,255,0.02);
      color: var(--text-secondary);
    }
    .faq-answer p {
      padding: 0 24px 20px;
    }
    .faq-item.active .faq-answer {
      max-height: 200px;
    }

    /* 联系表单 */
    .contact-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 48px;
    }
    .input-glass {
      background: rgba(10,14,39,0.7);
      border: 1px solid var(--border-light);
      border-radius: var(--radius-md);
      padding: 14px 16px;
      width: 100%;
      color: white;
      margin-bottom: 20px;
      transition: 0.2s;
    }
    .input-glass:focus {
      outline: none;
      border-color: var(--primary);
      box-shadow: 0 0 14px var(--primary-glow);
    }

    .footer {
      background: #060918;
      padding: 40px 0;
      text-align: center;
      color: var(--text-secondary);
      border-top: 1px solid var(--border-light);
    }
    @media (max-width: 1024px) {
      .hero-grid, .compare-row, .contact-grid { grid-template-columns: 1fr; }
      .cases-masonry { columns: 2; }
      .advantages-grid { grid-template-columns: repeat(2,1fr); }
    }
    @media (max-width: 768px) {
      h1 { font-size: 32px; } h2 { font-size: 28px; }
      .advantages-grid { grid-template-columns: 1fr; }
      .cases-masonry { columns: 1; }
    }