body {
font-family:helvetica, sans-serrif;
font-size:36px;
font-weight:bold;
}
a {
background-color:#FFFF00;
color:#000000;
padding:5px 50px;
text-decoration:none;
display:block;
margin: 10px auto;
width:150px;
}

a:hover{
background-color:#00FF00;
}