#pagetop_bt {
margin: 0px;
padding: 0px;
position:fixed;
z-index:100;
right:30px;
}
#pagetop_bt img{
filter: alpha(opacity=80);
}

#pagetop_bt{
transition: transform 500ms ease; 
}
#pagetop_bt:hover{transform: rotate(360deg);}