/* roulang page: index */
/* :root 设计变量 */
    :root {
      --primary-dark: #0A0E27;
      --bg-deeper: #060918;
      --accent-cyan: #00F0FF;
      --accent-magenta: #FF3CAC;
      --gradient-cta: linear-gradient(135deg, #FF3CAC, #784BA0);
      --text-primary: #E8ECF1;
      --text-secondary: #8892B0;
      --text-disabled: #4A5578;
      --card-bg: rgba(255, 255, 255, 0.03);
      --card-border: rgba(0, 240, 255, 0.12);
      --card-hover-border: rgba(0, 240, 255, 0.35);
      --card-shadow: 0 8px 32px rgba(0, 0, 0, 0.4);
      --card-hover-shadow: 0 12px 40px rgba(0, 240, 255, 0.15);
      --btn-primary-shadow: 0 4px 20px rgba(255, 60, 172, 0.4);
      --btn-primary-hover-shadow: 0 8px 30px rgba(255, 60, 172, 0.7);
      --font-sans: 'Inter', 'SF Pro Display', -apple-system, 'PingFang SC', 'Microsoft YaHei', sans-serif;
      --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
      --radius-sm: 8px;
      --radius-md: 16px;
      --radius-pill: 20px;
      --radius-lg: 24px;
      --max-width: 1200px;
      --section-gap: 100px;
    }

    * {
      box-sizing: border-box;
    }

    body {
      margin: 0;
      background-color: var(--bg-deeper);
      color: var(--text-primary);
      font-family: var(--font-sans);
      font-size: 16px;
      line-height: 1.75;
      -webkit-font-smoothing: antialiased;
      -moz-osx-font-smoothing: grayscale;
    }

    a {
      text-decoration: none;
      color: inherit;
      transition: color 0.2s;
    }
    a:hover {
      color: var(--accent-cyan);
    }

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

    button, input {
      font-family: inherit;
      outline: none;
      border: none;
      background: none;
    }

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

    /* 玻璃拟态卡片 */
    .glass-card {
      background: var(--card-bg);
      backdrop-filter: blur(20px) saturate(180%);
      -webkit-backdrop-filter: blur(20px) saturate(180%);
      border: 1px solid var(--card-border);
      border-radius: var(--radius-md);
      box-shadow: var(--card-shadow);
      transition: all 0.3s ease;
    }
    .glass-card:hover {
      border-color: var(--card-hover-border);
      box-shadow: var(--card-hover-shadow);
      transform: translateY(-6px);
    }

    /* 发光按钮 */
    .btn-primary {
      background: var(--gradient-cta);
      color: #FFFFFF;
      border-radius: var(--radius-sm);
      padding: 14px 32px;
      font-weight: 600;
      box-shadow: var(--btn-primary-shadow);
      transition: all 0.3s;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      cursor: pointer;
      border: none;
    }
    .btn-primary:hover {
      box-shadow: var(--btn-primary-hover-shadow);
      transform: translateY(-2px);
      color: #FFFFFF;
    }

    .btn-outline {
      background: transparent;
      border: 1.5px solid var(--accent-cyan);
      color: var(--accent-cyan);
      border-radius: var(--radius-sm);
      padding: 14px 32px;
      font-weight: 600;
      transition: all 0.3s;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      cursor: pointer;
    }
    .btn-outline:hover {
      background: rgba(0, 240, 255, 0.08);
      box-shadow: 0 4px 20px rgba(0, 240, 255, 0.3);
      color: var(--accent-cyan);
    }

    .btn-nav-cta {
      padding: 10px 20px;
      font-size: 14px;
    }

    .text-neon {
      background: linear-gradient(135deg, var(--accent-cyan), var(--accent-magenta));
      -webkit-background-clip: text;
      -webkit-text-fill-color: transparent;
      background-clip: text;
    }

    .bg-grid {
      background-image: 
        linear-gradient(rgba(255,255,255,0.02) 1px, transparent 1px),
        linear-gradient(90deg, rgba(255,255,255,0.02) 1px, transparent 1px);
      background-size: 40px 40px;
    }

    /* 自定义导航 */
    .navbar {
      background: rgba(10, 14, 39, 0.75);
      backdrop-filter: blur(20px);
      -webkit-backdrop-filter: blur(20px);
      border-bottom: 1px solid rgba(0, 240, 255, 0.1);
      position: sticky;
      top: 0;
      z-index: 100;
    }

    .nav-menu a {
      color: var(--text-secondary);
      font-weight: 500;
      padding: 0.5rem 1rem;
      transition: 0.2s;
    }
    .nav-menu a:hover {
      color: var(--accent-cyan);
    }

    .mobile-menu {
      background: var(--primary-dark);
    }

    /* 瀑布流 */
    .waterfall {
      column-gap: 24px;
      column-count: 3;
    }
    @media (max-width: 1024px) and (min-width: 769px) {
      .waterfall { column-count: 2; }
    }
    @media (max-width: 768px) {
      .waterfall { column-count: 1; }
    }

    .waterfall-item {
      break-inside: avoid;
      margin-bottom: 24px;
      display: inline-block;
      width: 100%;
    }

    /* FAQ 手风琴 */
    .faq-item {
      border-radius: var(--radius-md);
      overflow: hidden;
    }
    .faq-question {
      cursor: pointer;
      padding: 20px 24px;
      display: flex;
      justify-content: space-between;
      align-items: center;
      font-weight: 600;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.35s ease, padding 0.35s ease;
      color: var(--text-secondary);
      border-top: 1px solid transparent;
    }
    .faq-item.active .faq-answer {
      max-height: 200px;
      padding: 20px 24px;
      border-top: 1px solid rgba(255,255,255,0.06);
    }
    .faq-item.active .faq-question {
      color: var(--accent-cyan);
    }

    /* 响应式调整 */
    @media (max-width: 768px) {
      :root {
        --section-gap: 60px;
      }
      h1 { font-size: 36px !important; }
      h2 { font-size: 28px !important; }
    }
    .section {
      padding: var(--section-gap) 0;
    }

    footer a:hover {
      color: var(--accent-cyan);
    }

    .bg-radial-glow {
      background: radial-gradient(circle at 30% 50%, rgba(0,240,255,0.06) 0%, transparent 50%), 
                  radial-gradient(circle at 80% 20%, rgba(255,60,172,0.08) 0%, transparent 60%);
    }