.nach_oben_link {
    left:90%;
    top:90%;
    position:fixed;
    background-color:#0068b3;
    border:1px solid #fff;
    border-radius:50px;
    cursor: pointer;
        display: block;
        height: 45px;
        text-align: center;
        width: 45px;
        z-index: 1000;
}
.nach_oben_link a {
    font-size:40px;
    line-height:40px;
    text-decoration:none;
    color:#fff;
}
.nach_oben_link:hover {
    background-color:rgba(0,104,179,.7);
    font-size:30px;
    line-height:40px;
    text-decoration:none;
    color:#fff;
}