* {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
            font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
        }
        body {
            background-color: #f8fafc;
            color: #334155;
            line-height: 1.6;
            padding-bottom: 1.5rem;
        }
        .container {
            max-width: 1200px;
            margin: 0 auto;
            padding: 1.25rem;
        }
        .content-card {
            background: white;
            border-radius: 1rem;
            padding: 1.75rem;
            margin-bottom: 0.75rem; /* 核心修改：大幅减小章节间距 */
            box-shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1);
            border: 1px solid #e2e8f0;
        }
        h2 {
            color: #1e40af;
            font-size: 1.7rem;
            margin-bottom: 1rem;
            padding-bottom: 0.5rem;
            border-bottom: 2px solid #dbeafe;
        }
        h3 {
            color: #374151;
            font-size: 1.3rem;
            margin: 1.25rem 0 0.5rem;
        }
        p {
            margin-bottom: 0.85rem;
            font-size: 1.05rem;
        }
        .highlight-box {
            background: linear-gradient(to right, #dbeafe, #ede9fe);
            border-left: 4px solid #3b82f6;
            padding: 1.25rem;
            border-radius: 0 0.5rem 0.5rem 0;
            margin: 1.25rem 0;
        }
        ul, ol {
            margin: 0.75rem 0 1rem 1.5rem;
        }
        li {
            margin-bottom: 0.4rem;
            padding-left: 0.5rem;
        }
        .experiment-grid {
            display: grid;
            grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
            gap: 1.25rem;
            margin-top: 1.25rem;
        }
        .experiment-card {
            background: #f8fafc;
            border-radius: 0.75rem;
            padding: 1.25rem;
            border: 1px solid #e2e8f0;
            transition: transform 0.2s, box-shadow 0.2s;
        }
        .experiment-card:hover {
            transform: translateY(-4px);
            box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
        }
        .experiment-title {
            color: #1e40af;
            font-size: 1.25rem;
            margin-bottom: 0.75rem;
            display: flex;
            align-items: center;
            gap: 0.75rem;
        }
        .experiment-title::before {
            content: "🧪";
        }
        .materials-list {
            background: white;
            padding: 0.75rem 1rem;
            border-radius: 0.5rem;
            margin: 0.75rem 0;
            font-size: 0.95rem;
        }
        .step {
            display: flex;
            margin-bottom: 0.75rem;
        }
        .step-number {
            background: #3b82f6;
            color: white;
            border-radius: 50%;
            width: 1.75rem;
            height: 1.75rem;
            display: flex;
            align-items: center;
            justify-content: center;
            margin-right: 0.75rem;
            flex-shrink: 0;
            font-size: 0.9rem;
        }
        .stats-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
            gap: 1rem;
            margin: 1.25rem 0;
        }
        .stat-card {
            background: white;
            border-radius: 0.75rem;
            padding: 1.25rem;
            text-align: center;
            box-shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.08);
            border-top: 4px solid #8b5cf6;
        }
        .stat-value {
            font-size: 2rem;
            font-weight: 700;
            color: #1e40af;
            margin-bottom: 0.5rem;
        }
        .stat-label {
            font-size: 0.95rem;
            color: #64748b;
        }
        .product-showcase {
            background: linear-gradient(to right, #f0f9ff, #f5f3ff);
            border-radius: 1rem;
            padding: 1.75rem;
            margin: 1rem 0; /* 核心修改：减小产品展示区上下外边距 */
        }
        .product-title {
            color: #1e40af;
            font-size: 1.5rem;
            margin-bottom: 0.85rem;
        }
        footer {
            text-align: center;
            margin-top: 1.5rem;
            color: #64748b;
            font-size: 0.9rem;
            border-top: 1px solid #e2e8f0;
            padding-top: 1.25rem;
        }
        @media (max-width: 768px) {
            .container {
                padding: 1rem;
            }
            .content-card { 
                padding: 1.25rem; 
                margin-bottom: 0.75rem;
            }
            .experiment-grid { 
                grid-template-columns: 1fr; 
                gap: 1rem;
            }
            .stats-grid { 
                grid-template-columns: 1fr; 
                gap: 0.85rem;
            }
            .product-showcase {
                margin: 0.85rem 0;
                padding: 1.25rem;
            }
        }