body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
    background: #FFFFFF;
}
header, footer {
    background: #40dcd0 ;
    color: white;
    text-align: center;
    padding: 1em 0;
}
nav {
    background: #555;
    text-align: center;
    padding: 10px;
}
nav a {
    color: white;
    text-decoration: none;
    margin: 0 15px;
}
main {
    padding: 50px;
}