/* roulang page: index */
:root {
            --color-bg-main: #F8FAFC;
            --color-bg-card: #FFFFFF;
            --color-primary: #1E40AF;
            --color-primary-hover: #1D4ED8;
            --color-accent: #0284C7;
            --color-success: #10B981;
            --color-night: #0B132B;
            --color-text-title: #0F172A;
            --color-text-body: #334155;
            --color-text-muted: #64748B;
            --color-border: #E2E8F0;
            --radius-card: 1rem;
            --radius-btn: 0.625rem;
            --shadow-rest: 0 2px 10px -2px rgba(15, 23, 42, 0.04), 0 1px 3px -1px rgba(15, 23, 42, 0.03);
            --shadow-hover: 0 20px 25px -5px rgba(15, 23, 42, 0.08), 0 8px 10px -6px rgba(15, 23, 42, 0.04);
        }

        *, *::before, *::after {
            box-sizing: border-box;
        }

        body {
            background-color: var(--color-bg-main);
            color: var(--color-text-body);
            font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
            line-height: 1.65;
            margin: 0;
            padding: 0;
            overflow-x: hidden;
            -webkit-font-smoothing: antialiased;
        }

        h1, h2, h3, h4, h5, h6 {
            color: var(--color-text-title);
            line-height: 1.25;
            letter-spacing: -0.015em;
        }

        a {
            transition: color 0.2s ease, background-color 0.2s ease, border-color 0.2s ease, transform 0.2s ease, box-shadow 0.2s ease;
            text-decoration: none;
        }

        img {
            max-width: 100%;
            height: auto;
            display: block;
        }

        /* 统一容器与板块节奏 */
        .site-container {
            width: 100%;
            max-width: 1280px;
            margin-left: auto;
            margin-right: auto;
            padding-left: 1.25rem;
            padding-right: 1.25rem;
        }

        @media (min-width: 768px) {
            .site-container {
                padding-left: 2rem;
                padding-right: 2rem;
            }
        }

        .section-block {
            padding-top: 5rem;
            padding-bottom: 5rem;
            position: relative;
        }

        @media (min-width: 1024px) {
            .section-block {
                padding-top: 6.5rem;
                padding-bottom: 6.5rem;
            }
        }

        /* 卡片与悬浮态系统 */
        .surface-card {
            background-color: var(--color-bg-card);
            border: 1px solid var(--color-border);
            border-radius: var(--radius-card);
            box-shadow: var(--shadow-rest);
            transition: all 0.3s cubic-bezier(0.16, 1, 0.3, 1);
        }

        .surface-card:hover {
            transform: translateY(-4px);
            box-shadow: var(--shadow-hover);
            border-color: #CBD5E1;
        }

        /* 按钮体系 */
        .btn-primary {
            display: inline-flex;
            align-items: center;
            justify-content: center;
            gap: 0.5rem;
            background-color: var(--color-primary);
            color: #FFFFFF;
            font-weight: 600;
            padding: 0.75rem 1.5rem;
            border-radius: var(--radius-btn);
            box-shadow: 0 4px 12px rgba(30, 64, 175, 0.25);
            transition: all 0.25s ease;
        }

        .btn-primary:hover {
            background-color: var(--color-accent);
            transform: translateY(-1px);
            box-shadow: 0 8px 20px rgba(2, 132, 199, 0.32);
        }

        .btn-primary:focus-visible {
            outline: 2px solid var(--color-accent);
            outline-offset: 2px;
        }

        .btn-secondary {
            display: inline-flex;
            align-items: center;
            justify-content: center;
            gap: 0.5rem;
            background-color: rgba(255, 255, 255, 0.9);
            color: var(--color-text-title);
            border: 1px solid #CBD5E1;
            font-weight: 600;
            padding: 0.75rem 1.5rem;
            border-radius: var(--radius-btn);
            transition: all 0.25s ease;
        }

        .btn-secondary:hover {
            background-color: #F1F5F9;
            border-color: var(--color-primary);
            color: var(--color-primary);
        }

        /* 原生 details 手风琴动效 */
        details > summary {
            list-style: none;
        }
        details > summary::-webkit-details-marker {
            display: none;
        }
        details[open] summary ~ * {
            animation: accordionFade 0.28s ease-out;
        }
        @keyframes accordionFade {
            0% {
                opacity: 0;
                transform: translateY(-4px);
            }
            100% {
                opacity: 1;
                transform: translateY(0);
            }
        }

        /* 播放脉冲光环 */
        @keyframes pulseRing {
            0% {
                transform: scale(0.95);
                box-shadow: 0 0 0 0 rgba(2, 132, 199, 0.7);
            }
            70% {
                transform: scale(1);
                box-shadow: 0 0 0 18px rgba(2, 132, 199, 0);
            }
            100% {
                transform: scale(0.95);
                box-shadow: 0 0 0 0 rgba(2, 132, 199, 0);
            }
        }
        .play-trigger-ring {
            animation: pulseRing 2.2s infinite;
        }

        /* 步骤条连接线 */
        @media (min-width: 1024px) {
            .step-connector::after {
                content: '';
                position: absolute;
                top: 2rem;
                left: calc(50% + 2.25rem);
                width: calc(100% - 4.5rem);
                height: 2px;
                background: linear-gradient(90deg, #1E40AF 0%, #38BDF8 100%);
                opacity: 0.35;
                z-index: 0;
            }
        }

        /* 响应式适配补充 */
        @media (max-width: 768px) {
            .section-block {
                padding-top: 3.75rem;
                padding-bottom: 3.75rem;
            }
        }