#nach_oben{
    background-color: #006464;
    position: fixed;
    bottom: 20px;
    right: 20px;
    padding: 1em;
    z-index: 100;
    text-decoration: none;
    font-size: 12px;
    color: #FFFFFF;
    height: 50px;
    width: 50px;
    opacity: .75;


    border: 1px solid #c9c9c9;
    border-radius: 15px;
    transition: 1s;
}
#nach_oben p:hover { color: #FFFFFF; background-color: #343434; }