* {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }

        body {
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            line-height: 1.6;
            padding: 1.25rem;
            background-color: #f0f0f0;
            color: #333;
        }

        .back-btn {
            display: inline-block;
            padding: 0.75rem 1.5rem;
            background-color: #2c3e50;
            color: white;
            text-decoration: none;
            border-radius: 0.3125rem;
            margin-bottom: 1.25rem;
            transition: all 0.3s ease;
            font-weight: bold;
        }

        .back-btn:hover {
            background-color: #34495e;
            transform: translateY(-0.125rem);
            box-shadow: 0 0.25rem 0.5rem rgba(0,0,0,0.1);
        }

        h1, h2 {
            color: #2c3e50;
            margin: 1.25rem 0;
            font-weight: 600;
        }

        h1 {
            font-size: 2.5em;
            text-align: center;
            margin-bottom: 2.5rem;
            position: relative;
        }

        h1::after {
            content: '';
            display: block;
            width: 6.25rem;
            height: 0.25rem;
            background: #3498db;
            margin: 0.625rem auto;
            border-radius: 0.125rem;
        }

        .theory-section, .example-section {
            background-color: white;
            padding: 1.875rem;
            margin: 1.875rem 0;
            border-radius: 0.75rem;
            box-shadow: 0 0.25rem 0.9375rem rgba(0,0,0,0.1);
            transition: transform 0.3s ease;
        }

        .theory-section:hover, .example-section:hover {
            transform: translateY(-0.3125rem);
        }

        .theory-section {
            border-left: 0.3125rem solid #3498db;
        }

        .example-section {
            border-left: 0.3125rem solid #e74c3c;
        }

        .code-block {
            background-color: #2c3e50;
            color: #ecf0f1;
            padding: 1.25rem;
            border-radius: 0.5rem;
            margin: 0.9375rem 0;
            font-family: 'Courier New', monospace;
            position: relative;
            overflow: hidden;
            box-shadow: inset 0 0 0.625rem rgba(0,0,0,0.2);
        }

        .code-block::before {
            content: 'CSS';
            position: absolute;
            top: 0.3125rem;
            right: 0.625rem;
            color: rgba(255,255,255,0.3);
            font-size: 0.8em;
        }

        .demo-box {
            width: 18.75rem;
            height: 12.5rem;
            margin: 1.25rem auto;
            border: 0.125rem solid #333;
            transition: all 0.4s ease;
            cursor: pointer;
            position: relative;
        }

        .demo-box:hover {
            transform: scale(1.05) rotate(2deg);
            box-shadow: 0 0.5rem 1.25rem rgba(0,0,0,0.2);
        }

        .interactive-demo {
            display: flex;
            gap: 1.25rem;
            flex-wrap: wrap;
            justify-content: center;
            margin: 1.25rem 0;
        }

        .color-demo {
            width: 6.25rem;
            height: 6.25rem;
            margin: 0.625rem;
            border-radius: 0.5rem;
            transition: all 0.3s ease;
            cursor: pointer;
        }

        .color-demo:hover {
            transform: scale(1.1) rotate(10deg);
        }

        .blend-mode-demo {
            width: 18.75rem;
            height: 12.5rem;
            background-color: #3498db;
            background-image: url('https://picsum.photos/300/200');
            background-size: cover;
            margin: 0.625rem auto;
            transition: all 0.3s ease;
        }

        ul {
            list-style-position: inside;
            padding-left: 1.25rem;
        }

        li {
            margin: 0.625rem 0;
            position: relative;
            padding-left: 1.25rem;
        }

        li::before {
            content: '→';
            position: absolute;
            left: 0;
            color: #3498db;
        }

        .property-description {
            background-color: #f8f9fa;
            padding: 0.9375rem;
            border-radius: 0.5rem;
            margin: 0.625rem 0;
            border-left: 0.1875rem solid #3498db;
        }

        .color-demo-red {
            background-color: #ff0000;
        }
        .color-demo-red-transparent {
            background-color: rgba(255, 0, 0, 0.5);
        }
        .color-demo-red-hsl {
            background-color: hsl(0, 100%, 50%);
        }
        .gradient-demo-box {
            background-image: linear-gradient(45deg, #3498db, #2ecc71);
        }
        .repeat-demo-box {
            background-image: url('https://picsum.photos/50/50');
            background-repeat: repeat;
        }
        .cover-demo-box {
            background-image: url('https://picsum.photos/300/200');
            background-size: cover;
        }
        .position-demo-box {
            background-image: url('https://picsum.photos/100/100');
            background-repeat: no-repeat;
            background-position: center;
        }
        .scroll-container {
            height: 12.5rem;
            overflow-y: scroll;
            border: 0.0625rem solid #ccc;
            padding: 1.25rem;
        }
        .fixed-bg-content {
            height: 25rem;
            background-image: url('https://picsum.photos/300/300');
            background-attachment: fixed;
        }
        .fixed-bg-text {
            color: white;
            padding: 1.25rem;
        }
        .blend-mode-demo {
            background-blend-mode: multiply;
        }

        @media (max-width: 768px) {
            body {
                padding: 0.625rem;
            }

            .theory-section, .example-section {
                padding: 1.25rem;
            }

            .demo-box {
                width: 100%;
                max-width: 18.75rem;
            }
        }