/* roulang page: index */
:root {
            --primary: #E65100;
            --primary-hover: #CC4400;
            --primary-light: #FFF3E0;
            --bg-base: #F6F8FA;
            --bg-card: #FFFFFF;
            --bg-dark: #0D1117;
            --text-main: #111827;
            --text-muted: #4B5563;
            --border-color: #E5E7EB;
            --border-dark: #1F2937;
            --font-stack: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
        }

        body {
            font-family: var(--font-stack);
            background-color: var(--bg-base);
            color: var(--text-main);
            line-height: 1.75;
            overflow-x: hidden;
        }

        /* 斜切修饰 */
        .slant-cut {
            clip-path: polygon(0 0, 100% 0, 100% calc(100% - 3.5vw), 0 100%);
        }
        .slant-cut-reverse {
            clip-path: polygon(0 3.5vw, 100% 0, 100% 100%, 0 100%);
        }

        /* 动能橙高亮按钮 */
        .btn-kinetic {
            background-color: var(--primary);
            color: #FFFFFF;
            transition: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
        }
        .btn-kinetic:hover {
            background-color: var(--primary-hover);
            transform: translateY(-2px);
            box-shadow: 0 10px 20px -5px rgba(230, 81, 0, 0.35);
        }

        /* 精密卡片阴影与边框 */
        .tech-card {
            background: #FFFFFF;
            border: 1px solid var(--border-color);
            border-radius: 8px;
            transition: all 0.25s ease-in-out;
        }
        .tech-card:hover {
            transform: translateY(-4px);
            box-shadow: 0 12px 24px -8px rgba(0, 0, 0, 0.08);
            border-color: #CBD5E1;
        }

        /* 碳素深色卡片 */
        .tech-card-dark {
            background: #161B22;
            border: 1px solid var(--border-dark);
            border-radius: 8px;
            transition: all 0.25s ease-in-out;
        }
        .tech-card-dark:hover {
            transform: translateY(-4px);
            border-color: #374151;
            box-shadow: 0 12px 28px -6px rgba(0, 0, 0, 0.5);
        }

        /* 轮播过渡 */
        .carousel-slide {
            display: none;
            opacity: 0;
            transition: opacity 0.5s ease-in-out;
        }
        .carousel-slide.active {
            display: block;
            opacity: 1;
        }

        /* FAQ 手风琴展开动效 */
        .accordion-content {
            max-height: 0;
            overflow: hidden;
            transition: max-height 0.35s ease-out;
        }
        .accordion-item.active .accordion-content {
            max-height: 500px;
            transition: max-height 0.5s ease-in;
        }
        .accordion-item.active .accordion-icon {
            transform: rotate(180deg);
        }

        /* 移动端菜单抽屉 */
        #mobile-menu {
            transition: transform 0.3s ease-in-out;
        }