/* roulang page: index */
:root {
      --primary: #D41E3C;
      --primary-hover: #E8475A;
      --accent: #F5A623;
      --bg-deep: #0D0F14;
      --bg-card: #161920;
      --bg-light: #F0F1F5;
      --text-light: #E0E0E0;
      --text-dark: #1A1A2D;
      --text-muted: #9CA3AF;
      --border-subtle: rgba(255,255,255,0.06);
      --border-active: rgba(212,30,60,0.6);
      --radius-card: 0.5rem;
      --radius-btn: 0.375rem;
      --radius-tag: 0.25rem;
      --shadow-card: 0 4px 24px rgba(0,0,0,0.5);
      --shadow-hover: 0 8px 32px rgba(0,0,0,0.7);
    }
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }
    body {
      font-family: 'Inter', system-ui, -apple-system, 'Segoe UI', Roboto, sans-serif;
      background-color: var(--bg-deep);
      color: var(--text-light);
      line-height: 1.6;
      -webkit-font-smoothing: antialiased;
    }
    .container {
      max-width: 1280px;
      margin-left: auto;
      margin-right: auto;
      padding-left: 1.5rem;
      padding-right: 1.5rem;
    }
    img {
      max-width: 100%;
      height: auto;
      display: block;
    }
    a {
      text-decoration: none;
      color: inherit;
      transition: color 0.2s ease, background 0.2s ease, border-color 0.2s ease, transform 0.2s ease;
    }
    button, .btn {
      cursor: pointer;
      font-family: inherit;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      transition: all 0.25s ease;
      border: none;
      outline: none;
    }
    button:focus-visible, a:focus-visible, .btn:focus-visible {
      outline: 2px solid var(--primary);
      outline-offset: 2px;
    }
    /* 导航 */
    .navbar {
      background: rgba(13, 15, 20, 0.8);
      backdrop-filter: blur(12px);
      border-bottom: 1px solid var(--border-subtle);
    }
    .nav-link {
      position: relative;
      font-weight: 500;
      padding: 0.5rem 0.25rem;
      color: #ccc;
    }
    .nav-link:hover {
      color: white;
    }
    .active-nav {
      color: white;
    }
    .active-nav::after {
      content: '';
      position: absolute;
      left: 0;
      bottom: -4px;
      width: 100%;
      height: 2px;
      background: var(--primary);
    }
    .mobile-menu {
      background: rgba(13, 15, 20, 0.96);
      backdrop-filter: blur(20px);
    }
    /* 按钮 */
    .btn-primary {
      background: var(--primary);
      color: white;
      border-radius: var(--radius-btn);
      padding: 0.75rem 1.75rem;
      font-weight: 600;
      box-shadow: 0 4px 12px rgba(212,30,60,0.3);
    }
    .btn-primary:hover {
      background: var(--primary-hover);
      box-shadow: 0 6px 18px rgba(232,71,90,0.5);
      transform: translateY(-1px);
    }
    .btn-outline {
      background: transparent;
      border: 1px solid var(--primary);
      color: var(--primary);
      border-radius: var(--radius-btn);
      padding: 0.75rem 1.75rem;
      font-weight: 600;
    }
    .btn-outline:hover {
      background: rgba(212,30,60,0.1);
      color: white;
      border-color: var(--primary-hover);
    }
    /* 卡片 */
    .card-glass {
      background: var(--bg-card);
      border: 1px solid var(--border-subtle);
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-card);
      transition: all 0.3s ease;
    }
    .card-glass:hover {
      border-color: var(--border-active);
      box-shadow: var(--shadow-hover);
      transform: translateY(-4px);
    }
    .case-card {
      background: var(--bg-card);
      border-radius: var(--radius-card);
      overflow: hidden;
      box-shadow: var(--shadow-card);
      transition: transform 0.3s ease, box-shadow 0.3s ease;
    }
    .case-card:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-hover);
    }
    .case-card img {
      transition: transform 0.4s ease;
    }
    .case-card:hover img {
      transform: scale(1.03);
    }
    /* 标签 */
    .badge {
      background: var(--accent);
      color: #1A1A2D;
      font-size: 0.75rem;
      font-weight: 700;
      padding: 0.2rem 0.6rem;
      border-radius: 999px;
      letter-spacing: 0.3px;
    }
    .tag {
      font-size: 0.8rem;
      background: rgba(255,255,255,0.08);
      padding: 0.15rem 0.7rem;
      border-radius: 999px;
      color: #ccc;
    }
    /* FAQ */
    .faq-item {
      border-bottom: 1px solid var(--border-subtle);
    }
    .faq-question {
      font-weight: 700;
      cursor: pointer;
      padding: 1rem 0;
      display: flex;
      justify-content: space-between;
      align-items: center;
      color: white;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.35s ease, padding 0.35s ease;
      color: #bbb;
      line-height: 1.7;
    }
    .faq-item.active .faq-answer {
      max-height: 300px;
      padding-bottom: 1.25rem;
      border-left: 3px solid var(--primary);
      padding-left: 1rem;
      background: rgba(255,255,255,0.02);
    }
    .faq-icon {
      transition: transform 0.3s;
    }
    .faq-item.active .faq-icon {
      transform: rotate(45deg);
    }
    /* 对比卡片高亮 */
    .highlight-card {
      border: 2px solid var(--primary);
      box-shadow: 0 0 24px rgba(212,30,60,0.25);
      position: relative;
    }
    /* 背景光斑 */
    .hero-bg {
      background: radial-gradient(circle at 20% 30%, rgba(212,30,60,0.15) 0%, transparent 50%);
    }
    @media (max-width: 768px) {
      .container {
        padding-left: 1rem;
        padding-right: 1rem;
      }
    }