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

body {
    font-family: Arial, sans-serif;
    line-height: 1.6;
    color: #333;
    background-color: #f4f4f4;
}

header {
    background-color: #444;
    color: #FFFFFF;
    padding: 1em;
    text-align: center;
}

main {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 2em;
}

section {
    background-color: #fff;
    padding: 2em;
    margin-bottom: 20px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
}

h1 {
    color: #999999;
}

 h2 {
    color: #333;
}

p {
    margin-bottom: 20px;
}

pre {
    background-color: #f7f7f7;
    padding: 1em;
    border: 1px solid #ddd;
    border-radius: 10px;
}

.project-demo video {
    border: 1px solid #ddd;
    border-radius: 10px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
}

code {
    font-family: monospace;
    font-size: 16px;
}


 <style>
        /* Optimized CSS for cross-device compatibility */
        * {
            box-sizing: border-box;
            margin: 0;
            padding: 0;
            -webkit-tap-highlight-color: transparent;
        }

        body {
            font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
            line-height: 1.6;
            color: #333;
            background-color: #f4f4f4;
            min-height: 100vh;
            display: flex;
            flex-direction: column;
        }

        header {
            background-color: #444;
            color: #fff;
            padding: 1.5rem 1rem;
            text-align: center;
            box-shadow: 0 2px 5px rgba(0,0,0,0.1);
        }

        main {
            flex: 1;
            width: 100%;
            max-width: 1200px;
            margin: 0 auto;
            padding: 2rem 1rem;
        }

        section {
            background: #fff;
            padding: 2rem;
            margin: 1.5rem 0;
            border-radius: 12px;
            box-shadow: 0 4px 6px rgba(0,0,0,0.05);
            overflow: hidden;
        }

        h1 {
            color: #999;
            font-size: clamp(1.8rem, 4vw, 2.5rem);
            margin-bottom: 0.5rem;
        }

        h2 {
            color: #444;
            font-size: clamp(1.4rem, 3vw, 2rem);
            margin-bottom: 1.5rem;
        }

        p {
            margin-bottom: 1.5rem;
            line-height: 1.7;
            color: #666;
        }

        .project-demo video {
            width: 100%;
            height: auto;
            max-width: 800px;
            border-radius: 8px;
            display: block;
            margin: 0 auto;
            background: #000;
        }

        pre {
            background: #f8f9fa;
            padding: 1.5rem;
            border-radius: 8px;
            overflow-x: auto;
            -webkit-overflow-scrolling: touch;
            font-size: 0.9rem;
            line-height: 1.5;
            white-space: pre-wrap;
            word-wrap: break-word;
        }

        code {
            font-family: 'SFMono-Regular', Consolas, 'Liberation Mono', Menlo, monospace;
            color: #333;
        }

        footer {
            background: #444;
            color: #fff;
            text-align: center;
            padding: 1.5rem;
            margin-top: auto;
        }

        @media (max-width: 768px) {
            main {
                padding: 1.5rem 0.5rem;
            }

            section {
                padding: 1.5rem;
                margin: 1rem 0;
            }

            pre {
                padding: 1rem;
                font-size: 0.8rem;
            }

            h1 {
                font-size: 1.6rem;
            }

            h2 {
                font-size: 1.3rem;
            }
        }

        @media (max-width: 480px) {
            header {
                padding: 1rem;
            }

            section {
                padding: 1rem;
            }

            pre {
                padding: 0.8rem;
            }
        }
    </style>