/* roulang page: index */
:root {
      --bg-dark: #0B1120;
      --bg-surface: #0F172A;
      --accent-cyan: #06B6D4;
      --accent-blue: #3B82F6;
      --text-main: #F8FAFC;
      --text-muted: #94A3B8;
      --border-light: rgba(255, 255, 255, 0.08);
      --glass-bg: rgba(15, 23, 42, 0.75);
    }

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

    body {
      background-color: var(--bg-dark);
      color: var(--text-main);
      font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
      overflow-x: hidden;
      line-height: 1.6;
    }

    .glass-card {
      background: var(--glass-bg);
      backdrop-filter: blur(14px);
      -webkit-backdrop-filter: blur(14px);
      border: 1px solid var(--border-light);
      transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    }

    .glass-card:hover {
      border-color: rgba(6, 182, 212, 0.4);
      transform: translateY(-4px);
      box-shadow: 0 12px 30px rgba(6, 182, 212, 0.15);
    }

    .btn-glow {
      background: linear-gradient(135deg, #06B6D4 0%, #3B82F6 100%);
      box-shadow: 0 0 18px rgba(6, 182, 212, 0.4);
      transition: all 0.25s ease-in-out;
    }

    .btn-glow:hover {
      box-shadow: 0 0 28px rgba(6, 182, 212, 0.7);
      transform: translateY(-2px);
    }

    .btn-outline-glow {
      border: 1px solid rgba(6, 182, 212, 0.5);
      background: rgba(6, 182, 212, 0.05);
      transition: all 0.25s ease-in-out;
    }

    .btn-outline-glow:hover {
      background: rgba(6, 182, 212, 0.15);
      border-color: #06B6D4;
      box-shadow: 0 0 20px rgba(6, 182, 212, 0.3);
      transform: translateY(-2px);
    }

    .text-gradient {
      background: linear-gradient(135deg, #F8FAFC 20%, #06B6D4 70%, #3B82F6 100%);
      -webkit-background-clip: text;
      -webkit-text-fill-color: transparent;
    }

    .tech-border-top {
      border-top: 1px solid rgba(255, 255, 255, 0.06);
    }

    .stage-container {
      perspective: 1200px;
    }

    .stage-element {
      transform: rotateX(6deg);
      transition: transform 0.5s ease;
    }

    .stage-element:hover {
      transform: rotateX(0deg);
    }

    /* FAQ accordion transitions */
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.35s cubic-bezier(0, 1, 0, 1);
    }

    .faq-answer.open {
      max-height: 500px;
      transition: max-height 0.45s ease-in-out;
    }