```css
body {
    font-family: sans-serif;
    margin: 0;
    padding: 0;
    background-color: #f4f4f4;
    color: #333;
}
header {
    background-color: #007bff;
    color: white;
    padding: 20px;
    text-align: center;
}
main {
    padding: 20px;
    max-width: 800px;
    margin: 20px auto;
    background-color: white;
    border-radius: 8px;
    box-shadow: 0 0 10px rgba(0,0,0,0.1);
}
footer {
    text-align: center;
    padding: 10px;
    background-color: #ddd;
    position: fixed;
    bottom: 0;
    width: 100%;
}
```