/* roulang page: index */
:root {
      --primary-color: #1E293B;
      --accent-color: #F59E0B;
      --accent-hover: #D97706;
      --secondary-green: #10B981;
      --bg-base: #F8FAFC;
      --bg-midnight: #0F172A;
      --text-main: #0F172A;
      --text-muted: #475569;
      --border-subtle: rgba(15, 23, 42, 0.08);
      --card-radius: 20px;
      --shadow-ambient: 0 12px 32px -8px rgba(15, 23, 42, 0.06);
    }
    html {
      scroll-behavior: smooth;
      font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
    }
    body {
      background-color: var(--bg-base);
      color: var(--text-main);
      overflow-x: hidden;
    }
    .custom-card {
      border-radius: var(--card-radius);
      border: 1px solid var(--border-subtle);
      box-shadow: var(--shadow-ambient);
      transition: transform 0.25s ease, box-shadow 0.25s ease, border-color 0.25s ease;
    }
    .custom-card:hover {
      transform: translateY(-3px);
      box-shadow: 0 20px 40px -12px rgba(15, 23, 42, 0.1);
      border-color: rgba(245, 158, 11, 0.35);
    }
    .btn-amber {
      background-color: var(--accent-color);
      color: #FFFFFF;
      transition: background-color 0.2s ease, transform 0.2s ease, box-shadow 0.2s ease;
    }
    .btn-amber:hover {
      background-color: var(--accent-hover);
      transform: translateY(-2px);
      box-shadow: 0 8px 20px -4px rgba(245, 158, 11, 0.4);
    }
    .bg-midnight-section {
      background-color: var(--bg-midnight);
    }
    .nav-blur {
      backdrop-filter: blur(12px);
      -webkit-backdrop-filter: blur(12px);
      background: rgba(255, 255, 255, 0.94);
    }
    details > summary {
      list-style: none;
    }
    details > summary::-webkit-details-marker {
      display: none;
    }
    details[open] summary svg {
      transform: rotate(180deg);
    }