/* roulang page: index */
:root {
            --primary: #1e40af;
            --primary-dark: #0b192c;
            --accent: #0284c7;
            --accent-cyan: #06b6d4;
            --bg-light: #f8fafc;
            --text-main: #0f172a;
            --text-muted: #64748b;
            --border-color: #e2e8f0;
            --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
            --shadow-card: 0 10px 25px -5px rgba(15, 23, 42, 0.06), 0 8px 10px -6px rgba(15, 23, 42, 0.04);
            --shadow-hover: 0 20px 30px -10px rgba(15, 82, 186, 0.15);
        }
        html {
            scroll-behavior: smooth;
            font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans", sans-serif;
        }
        body {
            background-color: #ffffff;
            color: var(--text-main);
            overflow-x: hidden;
        }
        .card-shadow {
            box-shadow: var(--shadow-card);
            transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
        }
        .card-shadow:hover {
            transform: translateY(-4px);
            box-shadow: var(--shadow-hover);
            border-color: rgba(2, 132, 199, 0.35);
        }
        .text-gradient {
            background: linear-gradient(135deg, #1e40af 0%, #06b6d4 100%);
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
        }
        .btn-glow {
            transition: all 0.25s ease;
            box-shadow: 0 4px 14px rgba(15, 82, 186, 0.35);
        }
        .btn-glow:hover {
            box-shadow: 0 6px 20px rgba(6, 182, 212, 0.45);
            transform: translateY(-1px);
        }
        .tab-btn.active {
            background-color: #1e40af;
            color: #ffffff;
            border-color: #1e40af;
        }
        .tab-content {
            display: none;
        }
        .tab-content.active {
            display: grid;
        }
        .faq-answer {
            transition: max-height 0.3s ease-out;
            max-height: 0;
            overflow: hidden;
        }
        .faq-item.open .faq-answer {
            max-height: 240px;
        }
        .faq-item.open .faq-icon {
            transform: rotate(180deg);
        }