body {
    width: 800px;
    margin: 0 auto;
    background: #bbf;
}
header {
    background: #99f;
    color: white;
    text-align: center;
    padding: 15px;
    border-radius: 20px;
}
main {
    background: white;
    padding: 20px;
    border-radius: 7px;
    text-align: center;
}
nav a {
    background: #ddf;
}