ul#login_btn{
    margin: auto;
    padding: 0px;
    list-style: none;
    width: 81px;
}
ul#login_btn li{
    margin: auto;
    padding: 0;
    list-style: none;
    float: left;
}
ul#login_btn button{
    display: block;
    width: 81px;
    height: 22px;
    cursor: pointer;
    text-indent: -9999px;
}
button.login{
    background: url(index_lo.gif);
    border: 0;
}
button:hover.login{
    background-position: 0px -22px;
}