/* roulang page: index */
:root {
      --primary: #1d4ed8;
      --primary-hover: #1e40af;
      --accent: #0d9488;
      --accent-light: #ccfbf1;
      --dark-slate: #0f172a;
      --surface-light: #f8fafc;
      --text-main: #0f172a;
      --text-muted: #475569;
      --border-subtle: #e2e8f0;
    }

    html {
      scroll-behavior: smooth;
      font-family: system-ui, -apple-system, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
    }

    body {
      background-color: #ffffff;
      color: var(--text-main);
      overflow-x: hidden;
      line-height: 1.75;
    }

    .num-tabular {
      font-variant-numeric: tabular-nums;
      letter-spacing: -0.02em;
    }

    .glass-nav {
      background: rgba(255, 255, 255, 0.92);
      backdrop-filter: blur(12px);
      -webkit-backdrop-filter: blur(12px);
      border-bottom: 1px solid rgba(226, 232, 240, 0.8);
    }

    .hero-glow {
      background: radial-gradient(circle at 50% 30%, rgba(29, 78, 216, 0.08) 0%, rgba(255, 255, 255, 0) 70%);
    }

    .card-elevated {
      transition: transform 0.25s ease, box-shadow 0.25s ease, border-color 0.25s ease;
      border: 1px solid #e2e8f0;
    }
    .card-elevated:hover {
      transform: translateY(-4px);
      box-shadow: 0 16px 32px -8px rgba(15, 23, 42, 0.08);
      border-color: #cbd5e1;
    }

    .accordion-content {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s cubic-bezier(0, 1, 0, 1);
    }
    .accordion-item.active .accordion-content {
      max-height: 500px;
      transition: max-height 0.35s ease-in-out;
    }
    .accordion-item.active .chevron-icon {
      transform: rotate(180deg);
    }