body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
}
header {
    background: #007BFF;
    color: white;
    padding: 20px;
    text-align: center;
}
nav a {
    margin: 0 10px;
    color: white;
    text-decoration: none;
}
main {
    padding: 20px;
}
footer {
    background: #f1f1f1;
    text-align: center;
    padding: 10px;
}
.btn {
    display: inline-block;
    margin-top: 10px;
    padding: 10px 20px;
    background: green;
    color: white;
    text-decoration: none;
    border-radius: 5px;
}