body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
    background: #f7f7f7;
    color: #222;
}
header {
    background: #1976d2;
    color: #fff;
    padding: 20px 0 10px 0;
    text-align: center;
}
nav a {
    color: #fff;
    text-decoration: none;
    margin: 0 10px;
    font-weight: bold;
    transition: color 0.2s;
}
nav a:hover {
    color: #ffeb3b;
}
main {
    max-width: 700px;
    margin: 40px auto;
    background: #fff;
    padding: 30px;
    border-radius: 10px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.07);
}
footer {
    text-align: center;
    padding: 15px 0;
    background: #222;
    color: #fff;
    position: fixed;
    width: 100%;
    bottom: 0;
    left: 0;
}
@media (max-width: 600px) {
    main {
        padding: 15px;
        margin: 20px 5px;
    }
    header {
        padding: 15px 0 5px 0;
    }
}