body{
font-family: Arial;
background:#f5f6fa;
margin:0;
}
header{
background:#2c3e50;
color:white;
padding:15px;
}
nav a{
color:white;
margin:10px;
text-decoration:none;
}
main{
max-width:900px;
margin:auto;
background:white;
padding:20px;
}