/* roulang page: index */
:root {
      --primary: #F04E23;
      --primary-dark: #D13D1A;
      --primary-light: #FFF0EB;
      --dark: #1E1E1E;
      --accent: #FFC107;
      --gray-bg: #F5F3F0;
      --gray-light: #F9FAFB;
      --gray-border: #E5E7EB;
      --gray-text: #374151;
      --gray-muted: #6B7280;
      --white: #FFFFFF;
      --font-sans: "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
      --shadow-sm: 0 4px 12px rgba(0,0,0,0.04);
      --shadow-hover: 0 12px 24px rgba(240,78,35,0.08);
      --radius-md: 12px;
      --radius-btn: 8px;
      --transition: 0.3s ease;
    }

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

    body {
      font-family: var(--font-sans);
      font-size: 16px;
      line-height: 1.75;
      color: var(--gray-text);
      background-color: var(--white);
      scroll-behavior: smooth;
    }

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

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

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

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

    /* 导航栏 */
    #header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      z-index: 1000;
      background: rgba(30,30,30,0.88);
      backdrop-filter: blur(12px);
      transition: background 0.25s ease, box-shadow 0.25s ease;
      border-bottom: 1px solid rgba(255,255,255,0.08);
    }

    #header.scrolled {
      background: var(--dark);
      box-shadow: 0 4px 20px rgba(0,0,0,0.3);
    }

    .nav-container {
      display: flex;
      align-items: center;
      justify-content: space-between;
      height: 72px;
    }

    .logo {
      font-size: 1.8rem;
      font-weight: 700;
      color: var(--white);
      letter-spacing: 1px;
      white-space: nowrap;
    }
    .logo span {
      color: var(--primary);
      margin-left: 2px;
    }
    .logo i {
      font-size: 1.9rem;
      color: var(--primary);
      margin-right: 6px;
      vertical-align: middle;
    }

    .nav-menu {
      display: flex;
      align-items: center;
      gap: 2.2rem;
    }
    .nav-link {
      color: rgba(255,255,255,0.9);
      font-weight: 500;
      font-size: 0.98rem;
      padding: 8px 0;
      border-bottom: 2px solid transparent;
      transition: color 0.2s, border-color 0.2s;
    }
    .nav-link:hover {
      color: var(--white);
      border-bottom-color: var(--primary);
    }

    .btn-nav {
      background: var(--primary);
      color: white;
      padding: 10px 24px;
      border-radius: 30px;
      font-weight: 600;
      font-size: 0.95rem;
      box-shadow: 0 4px 12px rgba(240,78,35,0.4);
      margin-left: 8px;
    }
    .btn-nav:hover {
      background: var(--primary-dark);
      box-shadow: 0 8px 18px rgba(240,78,35,0.5);
    }

    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      cursor: pointer;
      background: transparent;
      border: none;
    }
    .hamburger span {
      width: 26px;
      height: 3px;
      background: white;
      border-radius: 3px;
      transition: 0.3s;
    }

    /* 英雄区 */
    #hero {
      min-height: 100vh;
      display: flex;
      align-items: center;
      justify-content: center;
      background: radial-gradient(circle at 30% 40%, #F04E23 0%, #1E1E1E 85%);
      position: relative;
      overflow: hidden;
      text-align: center;
    }
    .hero-bg-decor {
      position: absolute;
      inset: 0;
      background: url('/assets/images/backpic/back-1.webp') center/cover no-repeat;
      opacity: 0.18;
      mix-blend-mode: overlay;
    }
    .hero-content {
      position: relative;
      z-index: 2;
      max-width: 800px;
      color: white;
      padding: 24px;
    }
    .hero-title {
      font-size: 3.8rem;
      font-weight: 700;
      line-height: 1.2;
      margin-bottom: 1.2rem;
      text-shadow: 0 4px 20px rgba(0,0,0,0.5);
    }
    .hero-sub {
      font-size: 1.3rem;
      color: rgba(255,255,255,0.85);
      margin-bottom: 2.5rem;
    }
    .btn-group {
      display: flex;
      gap: 20px;
      justify-content: center;
      flex-wrap: wrap;
    }
    .btn-primary {
      background: var(--primary);
      color: white;
      padding: 16px 38px;
      border-radius: 40px;
      font-weight: 700;
      font-size: 1.1rem;
      box-shadow: 0 8px 22px rgba(240,78,35,0.45);
    }
    .btn-primary:hover {
      background: var(--primary-dark);
      transform: translateY(-2px);
    }
    .btn-outline {
      background: transparent;
      border: 2px solid var(--primary);
      color: white;
      padding: 16px 38px;
      border-radius: 40px;
      font-weight: 700;
      font-size: 1.1rem;
    }
    .btn-outline:hover {
      background: var(--primary-light);
      color: var(--primary);
      border-color: var(--primary);
    }

    /* 通用板块 */
    section {
      padding: 90px 0;
    }
    .section-title {
      font-size: 2.4rem;
      font-weight: 700;
      text-align: center;
      margin-bottom: 1rem;
      color: var(--dark);
    }
    .section-sub {
      text-align: center;
      color: var(--gray-muted);
      margin-bottom: 3.5rem;
      font-size: 1.1rem;
    }

    /* 功能卡片 */
    #features {
      background: var(--white);
    }
    .features-grid {
      display: grid;
      grid-template-columns: repeat(4,1fr);
      gap: 28px;
    }
    .feature-card {
      background: var(--white);
      border: 1px solid var(--gray-border);
      border-radius: var(--radius-md);
      padding: 2rem 1.5rem;
      text-align: center;
      box-shadow: var(--shadow-sm);
      transition: var(--transition);
    }
    .feature-card:hover {
      transform: translateY(-6px);
      box-shadow: var(--shadow-hover);
    }
    .feature-icon {
      font-size: 2.8rem;
      color: var(--primary);
      margin-bottom: 1.2rem;
    }
    .feature-card h3 {
      font-size: 1.4rem;
      font-weight: 600;
      margin-bottom: 0.7rem;
    }

    /* 场景 */
    #scenarios {
      background: var(--gray-bg);
    }
    .scenario-row {
      display: flex;
      align-items: center;
      gap: 50px;
      margin-bottom: 60px;
    }
    .scenario-img {
      flex: 1;
      border-radius: 20px;
      overflow: hidden;
      box-shadow: 0 10px 25px rgba(0,0,0,0.08);
    }
    .scenario-text {
      flex: 1;
    }
    .scenario-text h3 {
      font-size: 2rem;
      font-weight: 700;
      margin-bottom: 1rem;
    }

    /* 数据 */
    #cases {
      background: var(--white);
    }
    .stats-grid {
      display: flex;
      justify-content: space-around;
      flex-wrap: wrap;
      gap: 30px;
    }
    .stat-item {
      text-align: center;
    }
    .stat-number {
      font-size: 3.2rem;
      font-weight: 800;
      background: linear-gradient(135deg, var(--primary), var(--accent));
      -webkit-background-clip: text;
      -webkit-text-fill-color: transparent;
    }

    /* FAQ */
    #faq {
      background: var(--gray-light);
    }
    .faq-list {
      max-width: 800px;
      margin: 0 auto;
    }
    .faq-item {
      background: white;
      border-bottom: 1px solid var(--gray-border);
      padding: 20px 24px;
      cursor: pointer;
    }
    .faq-question {
      font-weight: 600;
      display: flex;
      justify-content: space-between;
      align-items: center;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: 0.3s;
      color: #4B5563;
    }
    .faq-item.active .faq-answer {
      max-height: 200px;
      padding-top: 12px;
    }

    /* CTA */
    #cta {
      background: var(--primary);
      text-align: center;
      color: white;
    }

    /* 页脚 */
    #footer {
      background: var(--dark);
      color: #ccc;
      padding: 50px 0 25px;
    }
    .footer-grid {
      display: flex;
      justify-content: space-between;
      flex-wrap: wrap;
      gap: 30px;
    }

    @media (max-width: 1024px) {
      .features-grid { grid-template-columns: repeat(2,1fr); }
    }
    @media (max-width: 768px) {
      .nav-menu { display: none; }
      .hamburger { display: flex; }
      .hero-title { font-size: 2.5rem; }
      .scenario-row { flex-direction: column; }
    }