.topbutton {
width:70px;
height: 70px;
border:50% solid #ccc;
padding: 6px;
text-align:center;
position:fixed;
bottom:20px;
left: 20px;
cursor:pointer;
color:#333;
opacity: 0.8;
background-color: #339900;
border-radius: 50%;
-moz-border-radius: 50%;
-webkit-border-radius: 50%;
-khtml-border-radius:50%;
}