/* roulang page: index */
/* ----- 设计变量 & 基础重置 ----- */
    :root {
      --primary: #0B1E33;
      --accent-green: #00E5A1;
      --accent-purple: #6C63FF;
      --bg-page: #F7F9FC;
      --bg-card: #FFFFFF;
      --border-light: #E9EDF3;
      --text-primary: #1E293B;
      --text-secondary: #64748B;
      --text-on-dark: #e2e8f0;
      --radius-lg: 16px;
      --radius-card: 16px;
      --radius-sm: 8px;
      --shadow-card: 0 4px 20px rgba(11,30,51,0.06);
      --shadow-hover: 0 12px 32px rgba(11,30,51,0.12);
      --transition-smooth: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    }

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

    body {
      font-family: 'Inter', 'PingFang SC', 'Microsoft YaHei', 'Helvetica Neue', sans-serif;
      background-color: var(--bg-page);
      color: var(--text-primary);
      line-height: 1.75;
      font-size: 16px;
      -webkit-font-smoothing: antialiased;
    }

    .container {
      max-width: 1280px;
      margin: 0 auto;
      padding: 0 32px;
    }

    h1, h2, h3 {
      font-family: 'PingFang SC', 'Microsoft YaHei', 'Helvetica Neue', sans-serif;
      letter-spacing: -0.01em;
    }

    h2 {
      font-size: 40px;
      font-weight: 600;
      color: var(--primary);
      margin-bottom: 16px;
    }

    h3 {
      font-size: 24px;
      font-weight: 600;
      color: var(--primary);
      line-height: 1.4;
    }

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

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

    button, .btn {
      cursor: pointer;
      font-family: inherit;
      border: none;
      border-radius: var(--radius-sm);
      transition: all var(--transition-smooth);
    }

    /* ----- 导航 (透明毛玻璃 → 滚动白底) ----- */
    .site-header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      z-index: 1000;
      height: 72px;
      display: flex;
      align-items: center;
      background: rgba(255, 255, 255, 0.25);
      backdrop-filter: blur(12px);
      -webkit-backdrop-filter: blur(12px);
      border-bottom: 1px solid rgba(233, 237, 243, 0.6);
      transition: background 0.3s, box-shadow 0.3s, height 0.3s;
    }

    .site-header.scrolled {
      background: rgba(255, 255, 255, 0.9);
      box-shadow: 0 4px 20px rgba(0,0,0,0.04);
      backdrop-filter: blur(14px);
    }

    .header-inner {
      display: flex;
      align-items: center;
      justify-content: space-between;
      width: 100%;
    }

    .logo {
      font-size: 28px;
      font-weight: 700;
      color: var(--primary);
      letter-spacing: -0.02em;
      display: flex;
      align-items: center;
      gap: 6px;
    }
    .logo-mark {
      display: inline-block;
      width: 8px;
      height: 8px;
      background-color: var(--accent-green);
      border-radius: 4px 0 4px 0;
      margin-right: 4px;
    }

    .nav-links {
      display: flex;
      gap: 40px;
    }

    .nav-links a {
      font-size: 15px;
      font-weight: 500;
      color: var(--text-primary);
      position: relative;
      padding: 6px 0;
      transition: color 0.2s;
    }

    .nav-links a::after {
      content: '';
      position: absolute;
      bottom: 0;
      left: 0;
      width: 0;
      height: 2px;
      background: var(--accent-green);
      transition: width var(--transition-smooth);
    }

    .nav-links a:hover {
      color: var(--accent-green);
    }
    .nav-links a:hover::after {
      width: 100%;
    }

    .btn-primary {
      background: var(--accent-green);
      color: var(--primary);
      padding: 12px 28px;
      font-weight: 600;
      font-size: 16px;
      box-shadow: none;
      border-radius: var(--radius-sm);
    }
    .btn-primary:hover {
      background: #00cc90;
      transform: scale(1.02);
    }

    .btn-outline {
      background: transparent;
      border: 1.5px solid var(--primary);
      color: var(--primary);
      padding: 12px 28px;
      font-weight: 600;
      border-radius: var(--radius-sm);
    }
    .btn-outline:hover {
      border-color: var(--accent-green);
      background: rgba(0, 229, 161, 0.08);
    }

    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      cursor: pointer;
    }
    .hamburger span {
      width: 24px;
      height: 2px;
      background: var(--primary);
      transition: 0.2s;
    }

    .mobile-menu {
      display: none;
      position: fixed;
      top: 72px;
      left: 0;
      width: 100%;
      height: calc(100vh - 72px);
      background: rgba(11, 30, 51, 0.92);
      backdrop-filter: blur(16px);
      flex-direction: column;
      align-items: center;
      justify-content: center;
      gap: 32px;
      z-index: 999;
    }
    .mobile-menu a {
      font-size: 24px;
      color: white;
      font-weight: 500;
    }

    @media (max-width: 768px) {
      .nav-links, .header-cta-desktop { display: none; }
      .hamburger { display: flex; }
    }

    /* ----- 首屏 Hero ----- */
    .hero {
      padding: 140px 0 100px;
      background: linear-gradient(135deg, #0B1E33 0%, #132B44 100%);
      position: relative;
      overflow: hidden;
      margin-bottom: 80px;
    }
    .hero::before {
      content: "";
      position: absolute;
      top:0;left:0;width:100%;height:100%;
      background-image: radial-gradient(rgba(255,255,255,0.06) 1px, transparent 1px);
      background-size: 32px 32px;
      opacity: 0.4;
    }
    .hero-grid {
      display: flex;
      align-items: center;
      gap: 60px;
      position: relative;
      z-index: 2;
    }
    .hero-text {
      flex: 1;
    }
    .hero-text h1 {
      font-size: 56px;
      font-weight: 700;
      color: white;
      line-height: 1.2;
      letter-spacing: -0.02em;
      margin-bottom: 24px;
    }
    .hero-sub {
      font-size: 18px;
      color: #cbd5e1;
      margin-bottom: 40px;
      max-width: 480px;
    }
    .hero-buttons {
      display: flex;
      gap: 16px;
      flex-wrap: wrap;
    }

    .hero-data {
      flex: 0.9;
      display: flex;
      gap: 20px;
      background: rgba(255,255,255,0.06);
      backdrop-filter: blur(8px);
      border-radius: 20px;
      padding: 28px 24px;
      border: 1px solid rgba(255,255,255,0.08);
    }
    .metric-card {
      text-align: center;
      flex: 1;
    }
    .metric-number {
      font-family: 'Inter', sans-serif;
      font-size: 42px;
      font-weight: 700;
      color: var(--accent-green);
      line-height: 1.2;
    }
    .metric-label {
      color: #94a3b8;
      font-size: 15px;
      margin-top: 8px;
    }

    @media (max-width: 1024px) {
      .hero-grid { flex-direction: column; text-align: center; }
      .hero-text h1 { font-size: 44px; }
      .hero-data { width: 100%; justify-content: center; }
    }

    /* ----- 核心优势 - 错层布局 ----- */
    .advantages {
      padding: 100px 0;
      background: var(--bg-page);
    }
    .adv-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 32px;
      align-items: start;
    }
    .card-large {
      background: white;
      border-radius: var(--radius-card);
      padding: 36px;
      box-shadow: var(--shadow-card);
      border-left: 6px solid var(--accent-green);
      grid-row: span 2;
    }
    .card-large .data-big {
      font-size: 48px;
      font-weight: 700;
      color: var(--accent-green);
      margin: 12px 0;
    }
    .small-cards {
      display: flex;
      flex-direction: column;
      gap: 24px;
    }
    .card-small {
      background: white;
      border-radius: var(--radius-card);
      padding: 28px;
      box-shadow: var(--shadow-card);
      transition: var(--transition-smooth);
    }
    .card-small:hover { transform: translateY(-5px); box-shadow: var(--shadow-hover); }
    .icon-accent { font-size: 24px; color: var(--accent-purple); margin-bottom: 12px; }

    @media (max-width: 768px) {
      .adv-grid { grid-template-columns: 1fr; }
    }

    /* ----- 服务矩阵 选项卡----- */
    .services {
      padding: 90px 0;
      background: white;
    }
    .tab-wrapper {
      display: flex;
      gap: 40px;
      margin-top: 40px;
    }
    .tab-nav {
      display: flex;
      flex-direction: column;
      min-width: 180px;
    }
    .tab-btn {
      background: transparent;
      padding: 16px 20px;
      text-align: left;
      font-weight: 600;
      color: var(--text-secondary);
      border-left: 3px solid transparent;
      transition: 0.2s;
    }
    .tab-btn.active {
      color: var(--accent-green);
      border-left-color: var(--accent-green);
      background: #f0fdf7;
    }
    .tab-content {
      background: var(--bg-card);
      border-radius: var(--radius-lg);
      padding: 32px;
      flex: 1;
      box-shadow: var(--shadow-card);
    }
    @media (max-width: 768px) {
      .tab-wrapper { flex-direction: column; }
      .tab-nav { flex-direction: row; overflow-x: auto; }
    }

    /* ----- Before/After 对比 ----- */
    .compare {
      padding: 90px 0;
    }
    .compare-panels {
      display: flex;
      gap: 24px;
      align-items: center;
      background: white;
      border-radius: 20px;
      padding: 32px;
      box-shadow: var(--shadow-card);
    }
    .panel {
      flex:1;
      padding: 24px;
    }
    .panel.before { background: #f1f5f9; border-radius: 12px; }
    .panel.after { background: #e6fefa; border-radius: 12px; border:1px solid var(--accent-green); }
    .vs-badge {
      font-weight: 700;
      color: var(--accent-purple);
    }
    @media (max-width: 768px) {
      .compare-panels { flex-direction: column; }
    }

    /* ----- FAQ 手风琴 ----- */
    .faq {
      padding: 90px 0;
      background: white;
    }
    .faq-list {
      max-width: 800px;
      margin: 0 auto;
    }
    .faq-item {
      border-bottom: 1px solid var(--border-light);
      padding: 20px 0;
    }
    .faq-question {
      display: flex;
      justify-content: space-between;
      font-weight: 600;
      cursor: pointer;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease;
      color: var(--text-secondary);
    }
    .faq-item.active .faq-answer { max-height: 200px; margin-top: 12px; }

    /* 表单卡片 */
    .contact {
      padding: 90px 0;
      background: linear-gradient(180deg, #f7f9fc 0%, #fff 100%);
    }
    .form-card {
      background: white;
      border-radius: 24px;
      padding: 48px;
      box-shadow: 0 20px 40px rgba(0,0,0,0.08);
      max-width: 700px;
      margin: 0 auto;
      border-top: 5px solid var(--accent-green);
    }
    .input-field {
      width: 100%;
      padding: 14px;
      margin: 12px 0 20px;
      border:1px solid #E2E8F0;
      border-radius: var(--radius-sm);
    }

    .footer {
      background: var(--primary);
      color: #cbd5e1;
      padding: 60px 0 30px;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: repeat(4,1fr);
      gap: 30px;
    }
    @media (max-width: 768px) {
      .footer-grid { grid-template-columns: 1fr; }
    }
    .fade-up { opacity: 0; transform: translateY(24px); transition: 0.6s ease; }
    .fade-up.visible { opacity: 1; transform: translateY(0); }