/* roulang page: index */
:root {
      --canvas-bg: #F7F8FA;
      --dark-obsidian: #0D0F12;
      --dark-carbon: #16191E;
      --core-cyan: #00E599;
      --accent-purple: #7A5AF8;
      --text-main: #0F172A;
      --text-secondary: #475569;
      --text-muted: #64748B;
      --border-light: rgba(15, 23, 42, 0.08);
      --border-dark: rgba(255, 255, 255, 0.08);
      --radius-sm: 6px;
      --radius-md: 12px;
      --radius-lg: 18px;
      --shadow-soft: 0 4px 20px rgba(0, 0, 0, 0.03);
      --shadow-hover: 0 12px 32px rgba(0, 229, 153, 0.12);
    }
    * { box-sizing: border-box; }
    body {
      font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
      background-color: var(--canvas-bg);
      color: var(--text-main);
      margin: 0;
      padding: 0;
      line-height: 1.6;
      -webkit-font-smoothing: antialiased;
    }
    a { color: inherit; text-decoration: none; transition: all 0.25s ease; }
    img { max-width: 100%; height: auto; display: block; }
    .site-container { max-width: 1240px; margin: 0 auto; padding: 0 24px; }
    .top-sub-header {
      height: 38px;
      background: #0F172A;
      color: #94A3B8;
      font-size: 13px;
      display: flex;
      align-items: center;
      border-bottom: 1px solid rgba(255, 255, 255, 0.05);
    }
    .top-sub-header a:hover { color: var(--core-cyan); }
    .version-badge {
      background: rgba(0, 229, 153, 0.15);
      color: var(--core-cyan);
      padding: 2px 8px;
      border-radius: 4px;
      font-size: 11px;
      font-weight: 600;
      margin-right: 12px;
    }
    .main-nav-bar {
      position: sticky;
      top: 0;
      z-index: 999;
      background: rgba(255, 255, 255, 0.94);
      backdrop-filter: blur(12px);
      border-bottom: 1px solid var(--border-light);
      padding: 14px 0;
    }
    .brand-logo {
      display: flex;
      align-items: center;
      gap: 10px;
      font-size: 19px;
      font-weight: 700;
      letter-spacing: -0.02em;
      color: var(--text-main);
    }
    .brand-logo i { color: var(--core-cyan); font-size: 22px; }
    .nav-links { display: flex; align-items: center; gap: 28px; list-style: none; margin: 0; padding: 0; }
    .nav-links a { font-size: 14px; font-weight: 500; color: var(--text-secondary); }
    .nav-links a:hover { color: var(--core-cyan); }
    .btn-main {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
      background: var(--core-cyan);
      color: var(--dark-obsidian);
      padding: 10px 22px;
      border-radius: var(--radius-sm);
      font-weight: 700;
      font-size: 14px;
      border: 1px solid transparent;
      cursor: pointer;
    }
    .btn-main:hover { background: #00ca84; color: #000; box-shadow: var(--shadow-hover); }
    .btn-secondary {
      display: inline-flex;
      align-items: center;
      gap: 8px;
      background: transparent;
      color: var(--text-main);
      padding: 10px 22px;
      border-radius: var(--radius-sm);
      font-weight: 600;
      font-size: 14px;
      border: 1px solid var(--border-light);
    }
    .btn-secondary:hover { background: rgba(15, 23, 42, 0.04); border-color: rgba(15, 23, 42, 0.2); }
    .section-wrap { padding: 90px 0; position: relative; }
    .section-dark { background: var(--dark-obsidian); color: #FFF; }
    .section-carbon { background: var(--dark-carbon); color: #FFF; }
    .section-head { margin-bottom: 54px; }
    .section-tag {
      display: inline-block;
      font-size: 12px;
      font-weight: 700;
      text-transform: uppercase;
      letter-spacing: 0.08em;
      color: var(--accent-purple);
      margin-bottom: 10px;
    }
    .section-dark .section-tag, .section-carbon .section-tag { color: var(--core-cyan); }
    .section-title {
      font-size: 32px;
      font-weight: 800;
      line-height: 1.3;
      letter-spacing: -0.02em;
      margin-bottom: 16px;
    }
    .section-desc { font-size: 15px; color: var(--text-secondary); max-width: 760px; line-height: 1.7; }
    .section-dark .section-desc, .section-carbon .section-desc { color: #94A3B8; }
    
    /* Hero */
    .hero-panel {
      padding: 80px 0 90px;
      background: linear-gradient(180deg, #FFFFFF 0%, #F1F4F9 100%);
      border-bottom: 1px solid var(--border-light);
    }
    .hero-h1 {
      font-size: 44px;
      font-weight: 800;
      line-height: 1.25;
      letter-spacing: -0.03em;
      margin-bottom: 22px;
      color: var(--text-main);
    }
    .hero-summary {
      font-size: 16px;
      line-height: 1.8;
      color: var(--text-secondary);
      margin-bottom: 34px;
    }
    .hero-trust-bar {
      margin-top: 48px;
      padding-top: 28px;
      border-top: 1px solid var(--border-light);
      display: flex;
      flex-wrap: wrap;
      gap: 36px;
      align-items: center;
    }
    .trust-metric-item { display: flex; align-items: baseline; gap: 8px; }
    .trust-metric-num { font-size: 24px; font-weight: 800; color: var(--text-main); font-variant-numeric: tabular-nums; }
    .trust-metric-label { font-size: 13px; color: var(--text-muted); }

    /* Cards & Grids */
    .feature-card {
      background: #FFFFFF;
      border: 1px solid var(--border-light);
      border-radius: var(--radius-md);
      padding: 30px;
      height: 100%;
      box-shadow: var(--shadow-soft);
      transition: all 0.3s ease;
    }
    .feature-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-hover); border-color: rgba(0, 229, 153, 0.4); }
    .feature-card-icon {
      width: 46px;
      height: 46px;
      border-radius: var(--radius-sm);
      background: rgba(0, 229, 153, 0.12);
      color: #009e66;
      display: flex;
      align-items: center;
      justify-content: center;
      font-size: 20px;
      margin-bottom: 20px;
    }
    .feature-card h3 { font-size: 18px; font-weight: 700; margin-bottom: 12px; }
    .feature-card p { font-size: 14px; color: var(--text-secondary); line-height: 1.65; margin: 0; }
    
    .dark-card {
      background: rgba(255, 255, 255, 0.03);
      border: 1px solid var(--border-dark);
      border-radius: var(--radius-md);
      padding: 28px;
      height: 100%;
      transition: all 0.3s ease;
    }
    .dark-card:hover { border-color: var(--core-cyan); background: rgba(255, 255, 255, 0.05); }
    .dark-card h3 { font-size: 18px; font-weight: 700; color: #FFF; margin-bottom: 12px; }
    .dark-card p { font-size: 14px; color: #94A3B8; line-height: 1.65; margin: 0; }

    /* Timeline Roadmap */
    .timeline-node {
      position: relative;
      padding-left: 28px;
      border-left: 2px solid rgba(0, 229, 153, 0.3);
      padding-bottom: 32px;
    }
    .timeline-node::before {
      content: "";
      position: absolute;
      left: -7px;
      top: 4px;
      width: 12px;
      height: 12px;
      border-radius: 50%;
      background: var(--core-cyan);
    }
    .timeline-node:last-child { border-left-color: transparent; }

    /* Comparison Table Panel */
    .compare-container {
      background: #111418;
      border: 1px solid var(--border-dark);
      border-radius: var(--radius-md);
      overflow: hidden;
    }
    .compare-row {
      display: grid;
      grid-template-columns: 1fr 1fr;
      padding: 20px 28px;
      border-bottom: 1px solid var(--border-dark);
      font-size: 14px;
    }
    .compare-row:last-child { border-bottom: none; }
    .compare-cell-old { color: #94A3B8; }
    .compare-cell-new { color: var(--core-cyan); font-weight: 600; }

    /* Accordion FAQ */
    .faq-panel { border-bottom: 1px solid var(--border-light); padding: 22px 0; }
    .faq-question { font-size: 17px; font-weight: 700; display: flex; justify-content: space-between; align-items: center; cursor: pointer; }
    .faq-answer { font-size: 14.5px; color: var(--text-secondary); margin-top: 12px; line-height: 1.7; }

    /* Forms */
    .cta-form-card {
      background: #FFFFFF;
      padding: 34px;
      border-radius: var(--radius-md);
      box-shadow: 0 16px 40px rgba(0,0,0,0.06);
      border: 1px solid var(--border-light);
    }
    .form-label { font-size: 13px; font-weight: 600; margin-bottom: 6px; display: block; }
    .form-input {
      width: 100%;
      padding: 12px 14px;
      border: 1px solid var(--border-light);
      border-radius: var(--radius-sm);
      font-size: 14px;
      margin-bottom: 18px;
      outline: none;
    }
    .form-input:focus { border-color: var(--core-cyan); }

    /* Footer */
    .site-footer {
      background: var(--dark-obsidian);
      color: #94A3B8;
      padding: 70px 0 35px;
      border-top: 1px solid var(--border-dark);
      font-size: 13.5px;
    }
    .footer-col h4 { color: #FFF; font-size: 15px; font-weight: 700; margin-bottom: 20px; }
    .footer-col ul { list-style: none; padding: 0; margin: 0; }
    .footer-col li { margin-bottom: 10px; }
    .footer-col a:hover { color: var(--core-cyan); }
    .footer-bottom {
      margin-top: 50px;
      padding-top: 25px;
      border-top: 1px solid rgba(255, 255, 255, 0.06);
      display: flex;
      flex-wrap: wrap;
      justify-content: space-between;
      align-items: center;
      gap: 16px;
    }

    @media (max-width: 840px) {
      .hero-h1 { font-size: 32px; }
      .section-title { font-size: 26px; }
      .compare-row { grid-template-columns: 1fr; gap: 10px; }
      .nav-links { display: none; }
    }