/* roulang page: index */
:root {
      --primary: #E43D2A;
      --primary-hover: #f54b38;
      --accent: #F5A623;
      --deep-bg: #0B0D14;
      --surface-glass: rgba(255, 255, 255, 0.04);
      --card-bg: rgba(255, 255, 255, 0.04);
      --text-primary: #F2F2F2;
      --text-secondary: #A0A3B1;
      --border-light: rgba(255, 255, 255, 0.08);
      --border-hover: rgba(228, 61, 42, 0.4);
      --radius-lg: 16px;
      --radius-md: 12px;
      --radius-sm: 8px;
      --shadow-card: 0 8px 32px rgba(0,0,0,0.4);
      --shadow-glow: 0 0 24px rgba(228,61,42,0.5);
      --font-heading: 'PingFang SC', 'Microsoft YaHei', 'Noto Sans SC', sans-serif;
      --font-body: 'PingFang SC', 'Microsoft YaHei', 'Inter', sans-serif;
      --transition-base: all 0.25s ease;
    }
    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }
    body {
      background-color: var(--deep-bg);
      color: var(--text-primary);
      font-family: var(--font-body);
      font-weight: 400;
      line-height: 1.75;
      font-size: 16px;
      -webkit-font-smoothing: antialiased;
      background-image: radial-gradient(circle at 20% 10%, rgba(228,61,42,0.08) 0%, transparent 45%), 
                        radial-gradient(circle at 80% 70%, rgba(245,166,35,0.06) 0%, transparent 40%);
    }
    .container {
      max-width: 1280px;
      margin: 0 auto;
      padding: 0 24px;
    }
    h1, h2, h3, h4 {
      font-family: var(--font-heading);
      font-weight: 700;
      margin-bottom: 0.5rem;
    }
    h2 {
      font-size: 2.2rem;
      letter-spacing: -0.02em;
      margin-bottom: 2rem;
    }
    a {
      color: var(--text-primary);
      text-decoration: none;
      transition: var(--transition-base);
    }
    img {
      max-width: 100%;
      display: block;
    }
    button, .btn {
      cursor: pointer;
      border: none;
      font-family: var(--font-body);
      font-weight: 600;
      transition: var(--transition-base);
    }
    /* glass card */
    .glass-card {
      background: rgba(255,255,255,0.04);
      backdrop-filter: blur(18px);
      border: 1px solid var(--border-light);
      border-radius: var(--radius-lg);
      box-shadow: var(--shadow-card);
      transition: transform 0.3s ease, box-shadow 0.3s ease, border-color 0.2s;
    }
    .glass-card:hover {
      transform: translateY(-6px);
      box-shadow: 0 16px 48px rgba(228,61,42,0.18);
      border-color: var(--border-hover);
    }
    /* buttons */
    .btn-primary {
      background: var(--primary);
      color: white;
      padding: 14px 32px;
      border-radius: var(--radius-sm);
      font-weight: 600;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      box-shadow: 0 4px 14px rgba(228,61,42,0.4);
    }
    .btn-primary:hover {
      background: var(--primary-hover);
      box-shadow: var(--shadow-glow);
      transform: translateY(-2px);
    }
    .btn-outline {
      background: transparent;
      border: 1px solid rgba(255,255,255,0.4);
      color: white;
      padding: 14px 32px;
      border-radius: var(--radius-sm);
      font-weight: 500;
      backdrop-filter: blur(8px);
    }
    .btn-outline:hover {
      background: rgba(255,255,255,0.08);
      border-color: rgba(255,255,255,0.8);
      color: white;
    }
    .btn-glass {
      background: rgba(255,255,255,0.08);
      backdrop-filter: blur(12px);
      border: 1px solid rgba(255,255,255,0.15);
      color: white;
      padding: 12px 28px;
      border-radius: 40px;
      font-weight: 500;
    }
    .btn-glass:hover {
      background: rgba(255,255,255,0.18);
      border-color: var(--accent);
      box-shadow: 0 0 18px rgba(245,166,35,0.35);
    }
    .nav {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      background: rgba(11,13,20,0.85);
      backdrop-filter: blur(22px);
      z-index: 100;
      border-bottom: 1px solid rgba(255,255,255,0.07);
      transition: background 0.3s;
      height: 72px;
      display: flex;
      align-items: center;
    }
    .nav.scrolled {
      background: rgba(11,13,20,0.95);
    }
    .nav .container {
      display: flex;
      justify-content: space-between;
      align-items: center;
      width: 100%;
    }
    .logo {
      font-family: var(--font-heading);
      font-weight: 800;
      font-size: 1.8rem;
      color: white;
      display: flex;
      align-items: center;
      gap: 8px;
    }
    .logo span {
      background: var(--primary);
      padding: 0 6px;
      border-radius: 6px;
    }
    .nav-links {
      display: flex;
      gap: 2.2rem;
      align-items: center;
    }
    .nav-links a {
      font-weight: 500;
      color: rgba(255,255,255,0.8);
      font-size: 0.98rem;
      border-bottom: 2px solid transparent;
    }
    .nav-links a:hover, .nav-links a.active {
      color: white;
      border-bottom-color: var(--primary);
    }
    .hamburger {
      display: none;
      flex-direction: column;
      gap: 6px;
      cursor: pointer;
      background: transparent;
    }
    .hamburger span {
      display: block;
      width: 26px;
      height: 2px;
      background: white;
      border-radius: 4px;
    }
    /* Hero */
    .hero {
      min-height: 100vh;
      display: flex;
      align-items: center;
      position: relative;
      background: radial-gradient(circle at 30% 40%, rgba(228,61,42,0.15) 0%, transparent 55%);
      padding-top: 80px;
    }
    .hero-content {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 3rem;
      align-items: center;
    }
    .hero-text h1 {
      font-size: 3.4rem;
      font-weight: 800;
      line-height: 1.2;
      color: white;
    }
    .highlight {
      color: var(--accent);
    }
    .hero-text p {
      color: var(--text-secondary);
      font-size: 1.2rem;
      margin: 1.8rem 0 2.2rem;
      max-width: 480px;
    }
    .hero-buttons {
      display: flex;
      gap: 18px;
      flex-wrap: wrap;
    }
    .hero-image {
      background: url('/assets/images/backpic/back-1.webp') center/cover no-repeat;
      border-radius: 24px;
      height: 380px;
      width: 100%;
      opacity: 0.85;
      box-shadow: 0 30px 50px rgba(0,0,0,0.5);
      border: 1px solid rgba(255,255,255,0.1);
    }
    section {
      padding: 100px 0;
    }
    .grid-4 {
      display: grid;
      grid-template-columns: repeat(4,1fr);
      gap: 28px;
      margin-top: 2.5rem;
    }
    .grid-3 {
      display: grid;
      grid-template-columns: repeat(3,1fr);
      gap: 2rem;
    }
    .feature-icon {
      font-size: 2rem;
      color: var(--accent);
      margin-bottom: 1.2rem;
    }
    .stat-number {
      font-size: 2.6rem;
      font-weight: 800;
      color: var(--primary);
    }
    .stats-row {
      display: flex;
      justify-content: space-around;
      flex-wrap: wrap;
      background: rgba(255,255,255,0.02);
      border-radius: 24px;
      padding: 40px 24px;
      backdrop-filter: blur(10px);
      margin-top: 2rem;
    }
    .faq-item {
      border-bottom: 1px solid var(--border-light);
      padding: 22px 0;
      cursor: pointer;
    }
    .faq-question {
      display: flex;
      align-items: center;
      gap: 12px;
      font-weight: 600;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.4s ease, padding 0.2s;
      color: var(--text-secondary);
    }
    .faq-item.open .faq-answer {
      max-height: 160px;
      padding-top: 12px;
    }
    .dot {
      width: 10px;
      height: 10px;
      background: var(--primary);
      border-radius: 50%;
　　}
    footer {
      background: rgba(0,0,0,0.6);
      backdrop-filter: blur(10px);
      padding: 60px 0 30px;
      border-top: 1px solid rgba(255,255,255,0.05);
      font-size: 0.95rem;
    }
    @media (max-width: 1024px) {
      .grid-4 { grid-template-columns: repeat(2,1fr); }
      .hero-content { grid-template-columns: 1fr; }
      .hero-text h1 { font-size: 2.8rem; }
    }
    @media (max-width: 768px) {
      .nav-links { display: none; }
      .hamburger { display: flex; }
      .grid-3 { grid-template-columns: 1fr; }
      .grid-4 { grid-template-columns: 1fr; }
      .hero-text h1 { font-size: 2.3rem; }
      .stats-row { flex-direction: column; gap: 24px; }
    }
    .mobile-menu {
      position: fixed; top:0; left:0; width:100%; height:100%;
      background: rgba(11,13,20,0.98); backdrop-filter: blur(30px);
      display: flex; flex-direction: column; align-items: center;
      justify-content: center; gap:2.5rem; z-index:200; display:none;
    }
    .mobile-menu a { font-size: 1.8rem; font-weight: 600; }