/* roulang page: index */
:root {
      --primary: #0A58CA;
      --primary-dark: #0848AA;
      --secondary: #06B6D4;
      --surface-bg: #F8FAFC;
      --card-bg: #FFFFFF;
      --text-main: #0F172A;
      --text-muted: #64748B;
      --border-color: #E2E8F0;
      --radius-sm: 6px;
      --radius-md: 10px;
      --radius-lg: 14px;
      --shadow-soft: 0 4px 20px -2px rgba(15, 23, 42, 0.05);
      --shadow-hover: 0 12px 28px -4px rgba(10, 88, 202, 0.12);
    }

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

    body {
      background-color: var(--surface-bg);
      color: var(--text-main);
      overflow-x: hidden;
    }

    .glass-nav {
      background: rgba(255, 255, 255, 0.94);
      backdrop-filter: blur(10px);
      -webkit-backdrop-filter: blur(10px);
    }

    .tech-card {
      background: var(--card-bg);
      border: 1px solid var(--border-color);
      border-radius: var(--radius-md);
      box-shadow: var(--shadow-soft);
      transition: all 0.28s ease;
    }

    .tech-card:hover {
      box-shadow: var(--shadow-hover);
      border-color: #BFDBFE;
      transform: translateY(-3px);
    }

    .badge-chip {
      display: inline-flex;
      align-items: center;
      padding: 0.25rem 0.65rem;
      font-size: 0.75rem;
      font-weight: 600;
      border-radius: 9999px;
      background: #EFF6FF;
      color: #1D4ED8;
      border: 1px solid #DBEAFE;
    }

    .accordion-content {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.35s ease-out, padding 0.35s ease;
    }

    .accordion-item.active .accordion-content {
      max-height: 240px;
      padding-top: 1rem;
    }

    .accordion-item.active .accordion-icon {
      transform: rotate(180deg);
    }