/* roulang page: index */
:root {
            --brand-purple: #4F46E5;
            --brand-cyan: #06B6D4;
            --text-main: #0F172A;
            --text-body: #334155;
            --text-muted: #64748B;
            --bg-light: #F8FAFC;
            --bg-dark: #0F172A;
            --border-color: #E2E8F0;
            --radius-main: 1rem;
            --shadow-card: 0 10px 25px -5px rgba(0, 0, 0, 0.05), 0 8px 10px -6px rgba(0, 0, 0, 0.05);
        }

        html {
            scroll-behavior: smooth;
        }

        body {
            font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
            color: var(--text-body);
            background-color: #FFFFFF;
            overflow-x: hidden;
        }

        /* 统一卡片悬浮动效 */
        .interactive-card {
            transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
        }
        .interactive-card:hover {
            transform: translateY(-6px);
            box-shadow: 0 20px 30px -10px rgba(79, 70, 229, 0.12);
        }

        /* 渐变文本高光 */
        .text-gradient {
            background: linear-gradient(135deg, #4F46E5 0%, #06B6D4 100%);
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
        }
        .text-gradient-cyan {
            background: linear-gradient(135deg, #22D3EE 0%, #38BDF8 100%);
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
        }

        /* 叠层卡片投影 */
        .stack-card-center {
            z-index: 20;
            box-shadow: 0 25px 50px -12px rgba(15, 23, 42, 0.25);
        }
        .stack-card-left {
            transform: rotate(-3deg) scale(0.96);
            z-index: 10;
        }
        .stack-card-right {
            transform: rotate(3deg) scale(0.96);
            z-index: 10;
        }

        /* 手风琴开关 */
        details[open] summary .faq-chevron {
            transform: rotate(180deg);
        }
        summary::-webkit-details-marker {
            display: none;
        }

        /* 背景微网格 */
        .bg-grid-pattern {
            background-image: radial-gradient(rgba(79, 70, 229, 0.12) 1px, transparent 1px);
            background-size: 24px 24px;
        }
        .bg-grid-dark {
            background-image: radial-gradient(rgba(6, 182, 212, 0.15) 1px, transparent 1px);
            background-size: 28px 28px;
        }