body{
font-family:Arial;
text-align:center;
background:#f4f4f4;
margin:0;
}

header{
background:#333;
color:white;
padding:20px;
}

main{
padding:30px;
}

nav{
background:#ddd;
padding:15px;
}

nav a{
text-decoration:none;
font-weight:bold;
margin:10px;
color:black;
}