/* roulang page: index */
/* ----- 设计变量 ----- */
    :root {
      --primary: #E03E2D;
      --primary-dark: #C53030;
      --secondary: #1A1A2E;
      --accent: #F5A623;
      --accent-light: #FDE9C8;
      --bg-light: #F9FAFB;
      --bg-gray: #F3F4F6;
      --white: #FFFFFF;
      --text-dark: #111827;
      --text-body: #4B5563;
      --text-muted: #9CA3AF;
      --text-on-dark: #E5E7EB;
      --border: #E5E7EB;
      --border-input: #D1D5DB;
      --shadow-sm: 0 1px 2px rgba(0,0,0,0.04);
      --shadow-md: 0 4px 12px rgba(0,0,0,0.06);
      --shadow-lg: 0 8px 24px rgba(0,0,0,0.08);
      --radius-sm: 8px;
      --radius-md: 12px;
      --radius-lg: 16px;
      --transition: 0.25s ease;
      --max-width: 1280px;
      --nav-height: 72px;
    }

    /* ----- 基础重置 ----- */
    *, *::before, *::after {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }

    html {
      scroll-behavior: smooth;
      scroll-padding-top: var(--nav-height);
    }

    body {
      font-family: "PingFang SC", "Microsoft YaHei", "Hiragino Sans GB", "Noto Sans SC", system-ui, -apple-system, sans-serif;
      background-color: var(--bg-light);
      color: var(--text-body);
      line-height: 1.75;
      font-size: 16px;
      font-weight: 400;
    }

    h1, h2, h3, h4 {
      color: var(--text-dark);
      line-height: 1.3;
    }

    h1 {
      font-size: 48px;
      font-weight: 800;
      letter-spacing: -0.5px;
    }

    h2 {
      font-size: 32px;
      font-weight: 700;
      margin-bottom: 16px;
      position: relative;
      display: inline-block;
    }

    h2::after {
      content: '';
      position: absolute;
      bottom: -8px;
      left: 0;
      width: 40px;
      height: 4px;
      background-color: var(--primary);
      border-radius: 2px;
    }

    h3 {
      font-size: 20px;
      font-weight: 600;
      margin-bottom: 8px;
    }

    p {
      margin-bottom: 16px;
      color: var(--text-body);
    }

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

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

    button, .btn {
      cursor: pointer;
      font-family: inherit;
      font-weight: 600;
      border: none;
      border-radius: var(--radius-sm);
      transition: all var(--transition);
      display: inline-flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
    }

    ul {
      list-style: none;
    }

    /* ----- 容器与布局 ----- */
    .container {
      max-width: var(--max-width);
      margin: 0 auto;
      padding: 0 24px;
    }

    .section {
      padding: 100px 0;
    }

    @media (max-width: 768px) {
      .section {
        padding: 70px 0;
      }
      h1 {
        font-size: 34px;
      }
      h2 {
        font-size: 26px;
      }
    }

    /* ----- 导航 (毛玻璃 + 响应式) ----- */
    .header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: var(--nav-height);
      background: rgba(255,255,255,0.92);
      backdrop-filter: blur(12px);
      -webkit-backdrop-filter: blur(12px);
      box-shadow: 0 1px 4px rgba(0,0,0,0.02);
      z-index: 1000;
      transition: background 0.3s;
    }

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

    .logo {
      font-size: 24px;
      font-weight: 800;
      color: var(--secondary);
      letter-spacing: -0.3px;
      white-space: nowrap;
    }
    .logo span {
      color: var(--primary);
    }

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

    .nav-links a {
      font-weight: 500;
      color: var(--text-body);
      font-size: 15px;
      position: relative;
    }

    .nav-links a::after {
      content: '';
      position: absolute;
      bottom: -4px;
      left: 0;
      width: 0;
      height: 2px;
      background: var(--primary);
      transition: width var(--transition);
    }

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

    .btn-primary {
      background: var(--primary);
      color: white;
      padding: 12px 28px;
      border-radius: var(--radius-sm);
      font-weight: 600;
      box-shadow: 0 2px 6px rgba(224,62,45,0.25);
    }
    .btn-primary:hover {
      background: var(--primary-dark);
      box-shadow: 0 4px 12px rgba(224,62,45,0.35);
      transform: translateY(-1px);
    }

    .hamburger {
      display: none;
      font-size: 26px;
      background: none;
      border: none;
      color: var(--secondary);
    }

    .mobile-menu {
      display: none;
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 100vh;
      background: var(--secondary);
      flex-direction: column;
      align-items: center;
      justify-content: center;
      gap: 32px;
      z-index: 999;
    }
    .mobile-menu.active {
      display: flex;
    }
    .mobile-menu a {
      color: white;
      font-size: 22px;
      font-weight: 600;
    }
    .close-menu {
      position: absolute;
      top: 24px;
      right: 24px;
      background: none;
      border: none;
      color: white;
      font-size: 32px;
    }

    @media (max-width: 768px) {
      .nav-links {
        display: none;
      }
      .hamburger {
        display: block;
      }
    }

    /* ----- Hero 左右分栏 ----- */
    .hero {
      padding-top: calc(var(--nav-height) + 40px);
      background-color: var(--bg-light);
    }
    .hero-grid {
      display: flex;
      align-items: center;
      gap: 48px;
    }
    .hero-left {
      flex: 1;
    }
    .hero-right {
      flex: 1;
      background: radial-gradient(circle at 30% 40%, rgba(224,62,45,0.08), transparent 60%);
      border-radius: var(--radius-lg);
      overflow: hidden;
      display: flex;
      align-items: center;
      justify-content: center;
    }
    .hero-right img {
      width: 100%;
      height: auto;
      object-fit: cover;
      border-radius: var(--radius-lg);
    }
    .hero-sub {
      font-size: 20px;
      color: var(--text-body);
      margin: 20px 0 32px;
    }
    .btn-group {
      display: flex;
      gap: 16px;
      flex-wrap: wrap;
    }
    .btn-outline {
      background: transparent;
      border: 2px solid var(--primary);
      color: var(--primary);
      padding: 12px 28px;
      border-radius: var(--radius-sm);
      font-weight: 600;
    }
    .btn-outline:hover {
      background: rgba(224,62,45,0.08);
    }

    @media (max-width: 768px) {
      .hero-grid {
        flex-direction: column;
        gap: 32px;
      }
      .hero-right {
        order: -1;
        width: 100%;
      }
    }

    /* 信任条 */
    .trust-bar {
      background: var(--bg-gray);
      padding: 32px 0;
    }
    .trust-grid {
      display: flex;
      justify-content: space-around;
      text-align: center;
      flex-wrap: wrap;
      gap: 24px;
    }
    .trust-item .number {
      font-size: 36px;
      font-weight: 800;
      color: var(--accent);
    }
    .trust-item .label {
      color: var(--text-body);
      font-weight: 500;
    }

    /* 功能卡片网格 */
    .features-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
      margin-top: 40px;
    }
    .feature-card {
      background: var(--white);
      padding: 32px 24px;
      border-radius: var(--radius-md);
      border: 1px solid var(--border);
      transition: all var(--transition);
    }
    .feature-card:hover {
      box-shadow: var(--shadow-lg);
      transform: translateY(-4px);
      border-color: transparent;
    }
    .icon-circle {
      width: 56px;
      height: 56px;
      background: rgba(224,62,45,0.1);
      border-radius: 50%;
      display: flex;
      align-items: center;
      justify-content: center;
      color: var(--primary);
      font-size: 24px;
      margin-bottom: 20px;
    }

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

    /* 场景图文交错 */
    .scene-row {
      display: flex;
      align-items: center;
      gap: 48px;
      margin-bottom: 60px;
    }
    .scene-row.reverse {
      flex-direction: row-reverse;
    }
    .scene-img {
      flex: 1;
      border-radius: var(--radius-lg);
      overflow: hidden;
    }
    .scene-img img {
      width: 100%;
      height: auto;
      object-fit: cover;
    }
    .scene-text {
      flex: 1;
    }
    .check-list li {
      display: flex;
      align-items: center;
      gap: 10px;
      margin-bottom: 12px;
      color: var(--text-body);
    }
    .check-list i {
      color: var(--primary);
    }

    @media (max-width: 768px) {
      .scene-row, .scene-row.reverse {
        flex-direction: column;
      }
    }

    /* 横向滑动案例 */
    .case-scroll {
      display: flex;
      gap: 24px;
      overflow-x: auto;
      padding: 20px 0 10px;
      scroll-snap-type: x mandatory;
    }
    .case-card {
      min-width: 300px;
      background: #F3F4F6;
      border-radius: var(--radius-md);
      padding: 24px;
      scroll-snap-align: start;
    }
    .case-header {
      display: flex;
      align-items: center;
      gap: 12px;
      margin-bottom: 16px;
    }
    .avatar {
      width: 44px;
      height: 44px;
      background: #ccc;
      border-radius: 50%;
    }
    .stars i {
      color: var(--accent);
      margin-right: 2px;
    }

    /* FAQ 手风琴 */
    .faq-item {
      border-bottom: 1px solid var(--border);
      padding: 18px 0;
    }
    .faq-question {
      display: flex;
      justify-content: space-between;
      align-items: center;
      font-weight: 600;
      cursor: pointer;
      color: var(--text-dark);
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease;
      color: var(--text-body);
      padding-top: 0;
    }
    .faq-item.active .faq-answer {
      max-height: 200px;
      padding-top: 12px;
    }

    /* CTA 横幅 */
    .cta-band {
      background: var(--secondary);
      color: white;
      text-align: center;
      padding: 80px 0;
      position: relative;
      overflow: hidden;
    }
    .cta-band h2 {
      color: white;
    }
    .cta-band h2::after {
      background: var(--accent);
      left: 50%;
      transform: translateX(-50%);
    }
    .btn-accent {
      background: var(--accent);
      color: var(--secondary);
      padding: 14px 32px;
      font-weight: 700;
      border-radius: var(--radius-sm);
    }

    /* 页脚 */
    .footer {
      background: var(--secondary);
      color: var(--text-on-dark);
      padding: 60px 0 30px;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 32px;
    }
    .footer-logo {
      font-size: 24px;
      font-weight: 800;
      color: white;
    }
    @media (max-width: 768px) {
      .footer-grid {
        grid-template-columns: 1fr;
      }
    }

    /* 图片占位回退 */
    .img-placeholder {
      background: linear-gradient(135deg, #E03E2D15, #1A1A2E10);
      width: 100%;
      min-height: 260px;
      border-radius: var(--radius-lg);
    }