/* roulang page: index */
/* 全局设计变量与基础重置 */
    :root {
      --primary-deep: #0A0E27;
      --accent-cyan: #00F0FF;
      --accent-coral: #FF4D6D;
      --bg-dark: #0A0E27;
      --bg-gradient: linear-gradient(135deg, #0A0E27 0%, #1A1F3A 100%);
      --text-light: #E2E8F0;
      --text-white: #FFFFFF;
      --text-dark: #1E293B;
      --card-light-bg: #F8FAFC;
      --border-light: rgba(255,255,255,0.08);
      --shadow-cyan: 0 4px 24px rgba(0,240,255,0.08);
      --shadow-card: 0 4px 20px rgba(0,0,0,0.04);
      --radius-lg: 12px;
      --radius-md: 8px;
      --space-section: 120px;
      --space-gutter: 24px;
      --container-max: 1280px;
      --font-title: 'PingFang SC', 'Microsoft YaHei', 'Noto Sans SC', sans-serif;
      --font-body: 'PingFang SC', 'Microsoft YaHei', 'Noto Sans SC', sans-serif;
      --font-number: 'Inter', 'DIN', sans-serif;
      --transition-smooth: 0.25s ease;
    }

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

    html {
      scroll-behavior: smooth;
    }

    body {
      font-family: var(--font-body);
      background-color: var(--bg-dark);
      color: var(--text-light);
      line-height: 1.6;
      font-size: 16px;
      -webkit-font-smoothing: antialiased;
      overflow-x: hidden;
    }

    .container {
      max-width: var(--container-max);
      margin: 0 auto;
      padding: 0 var(--space-gutter);
      width: 100%;
    }

    h1, h2, h3, h4 {
      font-family: var(--font-title);
      font-weight: 700;
      line-height: 1.3;
    }

    h1 {
      font-size: clamp(2.5rem, 6vw, 3.5rem);
    }
    h2 {
      font-size: clamp(2rem, 5vw, 2.5rem);
    }
    h3 {
      font-size: clamp(1.3rem, 3vw, 1.5rem);
    }

    p {
      font-size: 1rem;
      color: #CBD5E1;
      line-height: 1.7;
    }

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

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

    button, .btn {
      cursor: pointer;
      font-family: var(--font-body);
      font-weight: 600;
      border: none;
      outline: none;
      transition: var(--transition-smooth);
      display: inline-flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
      border-radius: var(--radius-md);
      padding: 0.8rem 2rem;
      font-size: 1rem;
    }

    /* 按钮系统 */
    .btn-primary {
      background-color: var(--accent-cyan);
      color: var(--primary-deep);
      box-shadow: 0 4px 14px rgba(0,240,255,0.3);
    }
    .btn-primary:hover {
      box-shadow: 0 0 24px rgba(0,240,255,0.7);
      transform: translateY(-2px);
    }

    .btn-outline {
      background: transparent;
      border: 2px solid var(--accent-cyan);
      color: var(--accent-cyan);
    }
    .btn-outline:hover {
      background: rgba(0,240,255,0.1);
    }

    .btn-coral {
      background-color: var(--accent-coral);
      color: white;
      box-shadow: 0 4px 14px rgba(255,77,109,0.4);
    }
    .btn-coral:hover {
      background-color: #E63950;
      box-shadow: 0 0 24px rgba(255,77,109,0.7);
      transform: translateY(-2px);
    }

    /* 导航 */
    .navbar {
      position: sticky;
      top: 0;
      z-index: 100;
      background: rgba(255,255,255,0.92);
      backdrop-filter: blur(12px);
      -webkit-backdrop-filter: blur(12px);
      border-bottom: 1px solid rgba(0,0,0,0.05);
      padding: 0.8rem 0;
    }
    .nav-container {
      display: flex;
      justify-content: space-between;
      align-items: center;
      max-width: var(--container-max);
      margin: 0 auto;
      padding: 0 var(--space-gutter);
    }
    .logo {
      font-family: var(--font-title);
      font-weight: 800;
      font-size: 1.8rem;
      color: var(--primary-deep);
      letter-spacing: 1px;
    }
    .logo span {
      color: var(--accent-cyan);
    }
    .nav-links {
      display: flex;
      align-items: center;
      gap: 2.5rem;
    }
    .nav-links a {
      font-weight: 500;
      color: #334155;
      position: relative;
    }
    .nav-links a:hover {
      color: var(--accent-cyan);
    }
    .nav-links a::after {
      content: '';
      position: absolute;
      bottom: -4px;
      left: 0;
      width: 0;
      height: 2px;
      background: var(--accent-cyan);
      transition: width 0.3s;
    }
    .nav-links a:hover::after {
      width: 100%;
    }
    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      cursor: pointer;
      background: none;
      border: none;
    }
    .hamburger span {
      width: 28px;
      height: 3px;
      background: var(--primary-deep);
      border-radius: 2px;
      transition: 0.3s;
    }

    /* Hero */
    .hero {
      background: var(--bg-gradient);
      padding: 4rem 0 6rem;
      position: relative;
      overflow: hidden;
    }
    .hero::before {
      content: '';
      position: absolute;
      top: 0;
      left: 0;
      width: 100%;
      height: 100%;
      background: radial-gradient(circle at 30% 40%, rgba(0,240,255,0.08) 0%, transparent 60%);
      pointer-events: none;
    }
    .hero-grid {
      display: grid;
      grid-template-columns: 1.1fr 0.9fr;
      gap: 3rem;
      align-items: center;
    }
    .hero-content h1 {
      color: white;
      margin-bottom: 1.5rem;
      line-height: 1.2;
    }
    .hero-highlight {
      color: var(--accent-cyan);
    }
    .hero-subtitle {
      font-size: 1.2rem;
      color: #CBD5E1;
      margin-bottom: 2.5rem;
      max-width: 500px;
    }
    .hero-buttons {
      display: flex;
      gap: 1.2rem;
      flex-wrap: wrap;
    }
    .hero-image img {
      border-radius: var(--radius-lg);
      box-shadow: 0 20px 40px rgba(0,240,255,0.15);
    }

    /* 通用板块 */
    .section {
      padding: var(--space-section) 0;
    }
    .section-light {
      background-color: #F8FAFC;
    }
    .section-dark {
      background-color: var(--bg-dark);
    }
    .section-title {
      text-align: center;
      margin-bottom: 3.5rem;
    }
    .section-title h2 {
      color: var(--text-dark);
      margin-bottom: 1rem;
    }
    .section-dark .section-title h2 {
      color: white;
    }
    .title-underline {
      width: 60px;
      height: 4px;
      background: var(--accent-cyan);
      margin: 0.8rem auto;
      border-radius: 2px;
    }
    .grid-3 {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 2rem;
    }
    .grid-2 {
      display: grid;
      grid-template-columns: repeat(2, 1fr);
      gap: 3rem;
      align-items: center;
    }

    /* 卡片 */
    .card {
      background: white;
      border-radius: var(--radius-lg);
      padding: 2rem;
      box-shadow: var(--shadow-card);
      transition: var(--transition-smooth);
    }
    .card:hover {
      transform: translateY(-6px);
      box-shadow: 0 12px 30px rgba(0,240,255,0.12);
    }
    .card-icon {
      font-size: 2.5rem;
      color: var(--accent-cyan);
      margin-bottom: 1.5rem;
    }
    .card h3 {
      color: var(--text-dark);
      margin-bottom: 0.8rem;
    }
    .feature-list {
      list-style: none;
      margin-top: 1.5rem;
    }
    .feature-list li {
      display: flex;
      align-items: center;
      gap: 0.8rem;
      margin-bottom: 0.8rem;
      color: #334155;
    }
    .feature-list li::before {
      content: '•';
      color: var(--accent-cyan);
      font-weight: bold;
      font-size: 1.4rem;
    }

    .scenario-card {
      position: relative;
      border-radius: var(--radius-lg);
      overflow: hidden;
      height: 320px;
      background-size: cover;
      background-position: center;
    }
    .scenario-overlay {
      background: linear-gradient(0deg, rgba(10,14,39,0.85) 0%, transparent 70%);
      position: absolute;
      bottom: 0;
      left: 0;
      width: 100%;
      padding: 2rem;
      color: white;
    }

    .stat-number {
      font-family: var(--font-number);
      font-weight: 800;
      font-size: 3rem;
      color: var(--accent-cyan);
      margin-bottom: 0.5rem;
    }
    .brand-wall {
      display: flex;
      flex-wrap: wrap;
      justify-content: center;
      gap: 2.5rem;
      margin-top: 2rem;
      filter: grayscale(1);
      opacity: 0.7;
    }
    .brand-wall img {
      height: 32px;
      width: auto;
    }

    /* FAQ */
    .faq-item {
      background: white;
      border-radius: var(--radius-md);
      margin-bottom: 1rem;
      overflow: hidden;
      box-shadow: 0 2px 8px rgba(0,0,0,0.02);
    }
    .faq-question {
      padding: 1.5rem;
      font-weight: 600;
      cursor: pointer;
      display: flex;
      justify-content: space-between;
      align-items: center;
      color: var(--text-dark);
      background: #F8FAFC;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.4s ease;
      background: white;
      padding: 0 1.5rem;
    }
    .faq-answer p {
      padding: 1rem 0;
      color: #475569;
    }
    .faq-item.active .faq-answer {
      max-height: 200px;
    }
    .faq-item.active .faq-question {
      border-left: 4px solid var(--accent-cyan);
    }

    .cta-section {
      background: var(--primary-deep);
      text-align: center;
      padding: 5rem 0;
    }
    .footer {
      background: #060B1C;
      color: #CBD5E1;
      padding: 3rem 0 1.5rem;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 2rem;
    }

    @media (max-width: 1024px) {
      .grid-3 { grid-template-columns: repeat(2,1fr); }
      .hero-grid { grid-template-columns: 1fr; }
      .hero-image { order: -1; max-width: 400px; margin: 0 auto; }
    }
    @media (max-width: 768px) {
      .nav-links { display: none; }
      .hamburger { display: flex; }
      .grid-2, .grid-3 { grid-template-columns: 1fr; }
      .footer-grid { grid-template-columns: 1fr; }
      :root { --space-section: 80px; }
    }