/* roulang page: index */
/* ----- 设计变量 ----- */
    :root {
      --primary-dark: #0F172A;
      --primary-dark-soft: #1E293B;
      --accent-orange: #F97316;
      --accent-orange-hover: #EA580C;
      --bg-light: #F8FAFC;
      --white: #FFFFFF;
      --text-main: #1E293B;
      --text-secondary: #64748B;
      --border-light: #E2E8F0;
      --shadow-sm: 0 4px 20px rgba(0, 0, 0, 0.04);
      --shadow-md: 0 8px 30px rgba(0, 0, 0, 0.08);
      --radius-lg: 16px;
      --radius-md: 12px;
      --radius-sm: 8px;
      --font-sans: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", sans-serif;
      --container-max: 1280px;
      --section-gap: 100px;
    }

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

    html {
      scroll-behavior: smooth;
    }

    body {
      font-family: var(--font-sans);
      background-color: var(--white);
      color: var(--text-main);
      line-height: 1.7;
      font-size: 16px;
      font-weight: 400;
      overflow-x: hidden;
    }

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

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

    .container {
      max-width: var(--container-max);
      margin: 0 auto;
      padding: 0 24px;
    }

    /* 导航栏 - 沉浸式透明到毛玻璃 */
    header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      z-index: 1000;
      transition: background 0.3s ease, box-shadow 0.3s ease, backdrop-filter 0.3s ease;
      padding: 16px 0;
      background: transparent;
    }

    header.scrolled {
      background: rgba(255, 255, 255, 0.85);
      backdrop-filter: blur(12px);
      box-shadow: 0 2px 20px rgba(0, 0, 0, 0.06);
      padding: 12px 0;
    }

    header .container {
      display: flex;
      align-items: center;
      justify-content: space-between;
    }

    .logo {
      font-size: 22px;
      font-weight: 700;
      color: white;
      letter-spacing: 0.5px;
      transition: color 0.3s;
    }
    header.scrolled .logo {
      color: var(--primary-dark);
    }

    .nav-links {
      display: flex;
      gap: 32px;
      align-items: center;
    }

    .nav-links a {
      font-weight: 500;
      font-size: 15px;
      color: rgba(255,255,255,0.9);
      position: relative;
      padding-bottom: 4px;
      transition: color 0.2s;
    }
    header.scrolled .nav-links a {
      color: var(--text-main);
    }
    .nav-links a::after {
      content: '';
      position: absolute;
      bottom: 0;
      left: 0;
      width: 0;
      height: 2px;
      background: var(--accent-orange);
      transition: width 0.25s ease;
    }
    .nav-links a:hover::after,
    .nav-links a.active::after {
      width: 100%;
    }
    .nav-links a:hover {
      color: var(--accent-orange);
    }
    header.scrolled .nav-links a:hover {
      color: var(--accent-orange);
    }

    .hamburger {
      display: none;
      font-size: 24px;
      cursor: pointer;
      color: white;
      background: none;
      border: none;
    }
    header.scrolled .hamburger {
      color: var(--primary-dark);
    }

    @media (max-width: 768px) {
      .nav-links {
        position: fixed;
        top: 0;
        right: -100%;
        width: 70%;
        height: 100vh;
        background: var(--primary-dark);
        flex-direction: column;
        justify-content: center;
        gap: 28px;
        transition: right 0.3s ease;
        box-shadow: -5px 0 20px rgba(0,0,0,0.2);
      }
      .nav-links.active {
        right: 0;
      }
      .nav-links a {
        color: white !important;
        font-size: 18px;
      }
      .hamburger {
        display: block;
        z-index: 1100;
      }
    }

    /* Hero 首屏 */
    #home {
      background: linear-gradient(135deg, #0F172A 0%, #1E293B 100%);
      min-height: 100vh;
      display: flex;
      align-items: center;
      position: relative;
      overflow: hidden;
      padding: 120px 0 80px;
    }

    .hero-particle {
      position: absolute;
      top: 10%;
      right: 5%;
      width: 300px;
      height: 300px;
      background: radial-gradient(circle, rgba(249,115,22,0.25) 0%, transparent 70%);
      border-radius: 50%;
      animation: float 8s infinite alternate;
    }
    @keyframes float {
      0% { transform: translateY(0px) scale(1); }
      100% { transform: translateY(-30px) scale(1.1); }
    }

    .hero-content {
      display: flex;
      align-items: center;
      gap: 48px;
      position: relative;
      z-index: 2;
    }
    .hero-text {
      flex: 1;
    }
    .hero-text h1 {
      font-size: 48px;
      font-weight: 800;
      line-height: 1.2;
      color: white;
      margin-bottom: 20px;
      letter-spacing: -0.5px;
    }
    .hero-text .highlight {
      color: var(--accent-orange);
    }
    .hero-subtitle {
      font-size: 18px;
      color: #CBD5E1;
      margin-bottom: 32px;
    }
    .hero-buttons {
      display: flex;
      gap: 16px;
      flex-wrap: wrap;
    }
    .btn-primary {
      background: var(--accent-orange);
      color: white;
      padding: 14px 32px;
      border-radius: var(--radius-md);
      font-weight: 600;
      border: none;
      cursor: pointer;
      transition: background 0.2s, box-shadow 0.2s;
      display: inline-flex;
      align-items: center;
      gap: 8px;
    }
    .btn-primary:hover {
      background: var(--accent-orange-hover);
      box-shadow: 0 8px 18px rgba(249,115,22,0.4);
    }
    .btn-outline {
      background: transparent;
      border: 2px solid var(--accent-orange);
      color: var(--accent-orange);
      padding: 14px 32px;
      border-radius: var(--md);
      font-weight: 600;
      transition: all 0.2s;
    }
    .btn-outline:hover {
      background: var(--accent-orange);
      color: white;
    }
    .hero-image {
      flex: 1;
      display: flex;
      justify-content: center;
    }
    .hero-image img {
      max-height: 520px;
      border-radius: 32px;
      box-shadow: 0 20px 40px rgba(0,0,0,0.5);
    }

    @media (max-width: 768px) {
      .hero-content {
        flex-direction: column;
        text-align: center;
      }
      .hero-text h1 {
        font-size: 32px;
      }
      .hero-buttons {
        justify-content: center;
      }
    }

    /* 通用板块 */
    section {
      padding: var(--section-gap) 0;
    }
    .section-title {
      font-size: 36px;
      font-weight: 700;
      margin-bottom: 16px;
      color: var(--primary-dark);
    }
    .section-desc {
      color: var(--text-secondary);
      margin-bottom: 48px;
      max-width: 700px;
    }

    /* 优势卡片 */
    .grid-3 {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
    }
    .advantage-card {
      background: var(--white);
      border: 1px solid var(--border-light);
      border-radius: var(--radius-lg);
      padding: 32px 24px;
      box-shadow: var(--shadow-sm);
      transition: box-shadow 0.3s;
    }
    .advantage-card:hover {
      box-shadow: var(--shadow-md);
    }
    .advantage-icon {
      font-size: 36px;
      color: var(--accent-orange);
      margin-bottom: 20px;
    }
    .advantage-card h3 {
      font-size: 22px;
      margin-bottom: 12px;
    }

    /* 功能亮点交替 */
    .feature-row {
      display: flex;
      align-items: center;
      gap: 48px;
      margin-bottom: 80px;
    }
    .feature-row.reverse {
      flex-direction: row-reverse;
    }
    .feature-img img {
      border-radius: 24px;
      box-shadow: var(--shadow-md);
    }
    .feature-text h3 {
      font-size: 28px;
      margin-bottom: 16px;
    }

    @media (max-width: 768px) {
      .grid-3 {
        grid-template-columns: 1fr;
      }
      .feature-row, .feature-row.reverse {
        flex-direction: column;
      }
    }

    /* 场景横向滚动 */
    .scenario-scroll {
      display: flex;
      gap: 24px;
      overflow-x: auto;
      padding-bottom: 16px;
    }
    .scenario-card {
      min-width: 260px;
      background: white;
      border-radius: var(--radius-lg);
      border-top: 4px solid var(--accent-orange);
      padding: 24px;
      box-shadow: var(--shadow-sm);
    }

    /* 数据看板 */
    .stats-grid {
      display: flex;
      justify-content: space-around;
      flex-wrap: wrap;
      gap: 32px;
      margin: 48px 0;
    }
    .stat-item {
      text-align: center;
    }
    .stat-number {
      font-size: 48px;
      font-weight: 800;
      color: var(--accent-orange);
    }

    /* FAQ */
    .faq-item {
      background: var(--bg-light);
      border-radius: var(--radius-md);
      margin-bottom: 16px;
      overflow: hidden;
    }
    .faq-question {
      padding: 20px;
      font-weight: 600;
      display: flex;
      justify-content: space-between;
      cursor: pointer;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease;
      background: white;
      padding: 0 20px;
    }
    .faq-answer.open {
      max-height: 200px;
      padding: 0 20px 20px;
    }

    /* CTA */
    #download {
      background: var(--primary-dark);
      text-align: center;
      color: white;
      padding: 80px 0;
    }
    .download-buttons {
      display: flex;
      justify-content: center;
      gap: 24px;
      flex-wrap: wrap;
      margin-top: 32px;
    }

    /* Footer */
    footer {
      background: var(--primary-dark);
      color: #CBD5E1;
      padding: 60px 0 30px;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 40px;
    }
    @media (max-width: 768px) {
      .footer-grid {
        grid-template-columns: 1fr;
      }
    }