/* roulang page: index */
/* ----- 设计变量与全局重置 ----- */
    :root {
      --primary-deep: #0A0E27;
      --primary-surface: #131833;
      --accent-red: #FF4655;
      --accent-red-hover: #E63946;
      --accent-cyan: #00E5FF;
      --bg-light: #F5F6FA;
      --card-white: #FFFFFF;
      --text-dark-title: #0A0E27;
      --text-dark-body: #4A4F6A;
      --text-light-title: #FFFFFF;
      --text-light-body: #B0B8D1;
      --text-muted: #6B7094;
      --border-light: #E8EAF0;
      --shadow-sm: 0 4px 20px rgba(0,0,0,0.04);
      --shadow-md: 0 12px 40px rgba(0,0,0,0.1);
      --shadow-red: 0 8px 30px rgba(255,70,85,0.4);
      --radius-card: 16px;
      --radius-btn: 50px;
      --radius-img: 12px;
      --font-title: 'Inter', 'PingFang SC', 'Microsoft YaHei', -apple-system, BlinkMacSystemFont, sans-serif;
      --font-body: 'Inter', 'PingFang SC', 'Microsoft YaHei', -apple-system, BlinkMacSystemFont, sans-serif;
      --transition: 0.3s ease;
    }

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

    html {
      scroll-behavior: smooth;
      font-size: 16px;
    }

    body {
      font-family: var(--font-body);
      line-height: 1.6;
      color: var(--text-dark-body);
      background-color: var(--bg-light);
      -webkit-font-smoothing: antialiased;
    }

    .container {
      max-width: 1200px;
      margin: 0 auto;
      padding: 0 24px;
    }

    img {
      max-width: 100%;
      display: block;
      height: auto;
      border-radius: var(--radius-img);
    }

    a {
      text-decoration: none;
      color: inherit;
      transition: var(--transition);
    }

    button, .btn {
      cursor: pointer;
      font-family: var(--font-body);
      border: none;
      outline: none;
      transition: all 0.25s ease;
    }

    /* 板块通用间距 */
    section {
      padding: 100px 0;
    }

    @media (max-width: 768px) {
      section {
        padding: 70px 0;
      }
    }

    /* ----- 导航栏 ----- */
    .navbar {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      z-index: 1000;
      height: 72px;
      background: rgba(255,255,255,0.85);
      backdrop-filter: blur(20px);
      border-bottom: 1px solid var(--border-light);
      transition: background 0.3s, box-shadow 0.3s;
      display: flex;
      align-items: center;
    }

    .navbar.scrolled {
      background: #FFFFFF;
      box-shadow: 0 2px 20px rgba(0,0,0,0.06);
    }

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

    .logo {
      font-family: var(--font-title);
      font-weight: 700;
      font-size: 1.5rem;
      color: var(--text-dark-title);
      letter-spacing: -0.02em;
      display: flex;
      align-items: center;
      gap: 8px;
    }
    .logo i {
      color: var(--accent-red);
      font-size: 2rem;
    }

    .nav-menu {
      display: flex;
      gap: 36px;
      align-items: center;
    }

    .nav-link {
      font-weight: 500;
      font-size: 0.95rem;
      color: var(--text-dark-body);
      position: relative;
      padding: 8px 0;
    }

    .nav-link::after {
      content: '';
      position: absolute;
      bottom: 0;
      left: 50%;
      transform: translateX(-50%) scaleX(0);
      width: 100%;
      height: 2px;
      background: var(--accent-red);
      transition: transform 0.25s ease;
    }

    .nav-link:hover {
      color: var(--accent-red);
    }
    .nav-link:hover::after {
      transform: translateX(-50%) scaleX(1);
    }

    .btn-nav {
      background: var(--accent-red);
      color: white;
      padding: 10px 24px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      font-size: 0.9rem;
    }
    .btn-nav:hover {
      background: var(--accent-red-hover);
      transform: scale(1.05);
    }

    .hamburger {
      display: none;
      font-size: 1.8rem;
      color: var(--text-dark-title);
      background: none;
      border: none;
    }

    @media (max-width: 1024px) {
      .nav-menu {
        gap: 24px;
      }
    }

    @media (max-width: 768px) {
      .hamburger {
        display: block;
      }
      .nav-menu {
        position: fixed;
        top: 72px;
        left: 0;
        width: 100%;
        background: var(--primary-deep);
        flex-direction: column;
        padding: 32px 24px;
        gap: 24px;
        transform: translateY(-150%);
        opacity: 0;
        transition: transform 0.4s ease, opacity 0.3s;
        border-bottom: 2px solid var(--accent-red);
      }
      .nav-menu.active {
        transform: translateY(0);
        opacity: 1;
      }
      .nav-link {
        color: white !important;
        font-size: 1.2rem;
      }
      .btn-nav {
        display: inline-block;
        width: fit-content;
      }
    }

    /* ----- Hero 首屏 ----- */
    .hero {
      min-height: 100vh;
      background: linear-gradient(135deg, var(--primary-deep) 0%, var(--primary-surface) 100%);
      display: flex;
      align-items: center;
      justify-content: center;
      text-align: center;
      position: relative;
      overflow: hidden;
      padding-top: 72px;
    }

    .hero::before {
      content: '';
      position: absolute;
      width: 600px;
      height: 600px;
      background: radial-gradient(circle, rgba(0,229,255,0.18) 0%, transparent 70%);
      top: -100px;
      right: -100px;
      animation: floatGlow 6s infinite alternate;
    }

    .hero::after {
      content: '';
      position: absolute;
      width: 500px;
      height: 500px;
      background: radial-gradient(circle, rgba(255,70,85,0.1) 0%, transparent 70%);
      bottom: -80px;
      left: -120px;
      animation: floatGlow 8s infinite alternate-reverse;
    }

    @keyframes floatGlow {
      0% { transform: translate(0,0) scale(1); opacity: 0.6; }
      100% { transform: translate(30px, -40px) scale(1.2); opacity: 0.9; }
    }

    .hero-content {
      position: relative;
      z-index: 2;
      max-width: 800px;
      padding: 0 20px;
    }

    .hero h1 {
      font-family: var(--font-title);
      font-size: 3.5rem;
      font-weight: 800;
      color: var(--text-light-title);
      letter-spacing: -0.03em;
      line-height: 1.2;
      animation: fadeUp 0.8s ease;
    }

    .hero .subtitle {
      font-size: 1.2rem;
      color: var(--text-light-body);
      margin: 24px 0 36px;
      animation: fadeUp 0.8s 0.2s ease both;
    }

    .btn-group {
      display: flex;
      gap: 20px;
      justify-content: center;
      flex-wrap: wrap;
      animation: fadeUp 0.8s 0.35s ease both;
    }

    .btn-primary {
      background: var(--accent-red);
      color: white;
      padding: 16px 48px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      font-size: 1.1rem;
    }
    .btn-primary:hover {
      background: var(--accent-red-hover);
      box-shadow: var(--shadow-red);
      transform: translateY(-2px);
    }

    .btn-secondary {
      background: transparent;
      border: 2px solid var(--accent-red);
      color: var(--accent-red);
      padding: 14px 40px;
      border-radius: var(--radius-btn);
      font-weight: 600;
    }
    .btn-secondary:hover {
      background: var(--accent-red);
      color: white;
    }

    .trust-signal {
      margin-top: 40px;
      color: var(--text-muted);
      font-size: 0.9rem;
    }

    @keyframes fadeUp {
      from { opacity: 0; transform: translateY(25px); }
      to { opacity: 1; transform: translateY(0); }
    }

    @media (max-width: 768px) {
      .hero h1 {
        font-size: 2.5rem;
      }
    }

    /* ----- 核心优势 非对称栅格 ----- */
    .features-grid {
      display: grid;
      grid-template-columns: 1fr 1fr 1fr;
      gap: 28px;
      margin-top: 48px;
    }

    .feature-card {
      background: var(--card-white);
      border-radius: var(--radius-card);
      padding: 36px 28px;
      box-shadow: var(--shadow-sm);
      transition: var(--transition);
    }
    .feature-card:hover {
      transform: translateY(-6px);
      box-shadow: var(--shadow-md);
    }
    .feature-card.large {
      grid-row: span 2;
      display: flex;
      flex-direction: column;
      justify-content: center;
      background: var(--primary-deep);
      color: white;
    }
    .feature-card.large h3, .feature-card.large p {
      color: var(--text-light-body);
    }
    .feature-icon {
      font-size: 2.5rem;
      color: var(--accent-cyan);
      margin-bottom: 20px;
    }
    .feature-card h3 {
      font-size: 1.4rem;
      font-weight: 600;
      color: var(--text-dark-title);
      margin-bottom: 12px;
    }
    .feature-card p {
      color: var(--text-muted);
      font-size: 1rem;
    }

    @media (max-width: 768px) {
      .features-grid {
        grid-template-columns: 1fr;
      }
      .feature-card.large {
        grid-row: span 1;
      }
    }

    /* 功能分组卡片网格 */
    .service-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 24px;
      margin-top: 48px;
    }
    .service-card {
      background: white;
      border-radius: var(--radius-card);
      overflow: hidden;
      box-shadow: var(--shadow-sm);
      transition: var(--transition);
    }
    .service-card:hover {
      transform: translateY(-6px);
      box-shadow: var(--shadow-md);
    }
    .service-card img {
      width: 100%;
      height: 180px;
      object-fit: cover;
    }
    .service-info {
      padding: 20px;
    }
    @media (max-width: 1024px) {
      .service-grid { grid-template-columns: repeat(2, 1fr); }
    }
    @media (max-width: 520px) {
      .service-grid { grid-template-columns: 1fr; }
    }

    /* 使用场景 左右交替 */
    .scenario-row {
      display: flex;
      align-items: center;
      gap: 60px;
      margin-bottom: 80px;
    }
    .scenario-row.reverse {
      flex-direction: row-reverse;
    }
    .scenario-img {
      flex: 1;
    }
    .scenario-text {
      flex: 1;
    }
    @media (max-width: 768px) {
      .scenario-row, .scenario-row.reverse {
        flex-direction: column;
      }
    }

    /* 案例与价格卡片省略详细但完整存在 */
    .stats-grid {
      display: flex;
      gap: 30px;
      justify-content: center;
      flex-wrap: wrap;
    }
    .stat-card {
      background: #F5F6FA;
      padding: 28px;
      border-radius: 12px;
      text-align: center;
    }
    .price-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
      margin-top: 40px;
    }
    .price-card.featured {
      border: 2px solid var(--accent-red);
      transform: scale(1.05);
    }
    @media (max-width: 768px) {
      .price-grid { grid-template-columns: 1fr; }
    }

    /* FAQ 双列 */
    .faq-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 20px;
      margin-top: 40px;
    }
    .faq-item {
      background: white;
      border-radius: 12px;
      padding: 18px 22px;
      cursor: pointer;
    }
    @media (max-width: 768px) {
      .faq-grid { grid-template-columns: 1fr; }
    }

    /* 页脚 */
    footer {
      background: var(--primary-deep);
      color: var(--text-muted);
      padding: 60px 0 30px;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 30px;
    }
    @media (max-width: 768px) {
      .footer-grid { grid-template-columns: 1fr 1fr; }
    }