#butter-scroll {
    display: block;
    background-color: #2196F3;
    border-radius: 50%;
    width: 35px;
    height: 35px;

    position: fixed;
    bottom: 2%;
    right: 50%;
    z-index: 100;

    opacity: .8;

    box-shadow: 0px 0px 5px 3px rgba(0, 0, 0, 0.7);
}
#butter-scroll a {
    color: white;
    line-height: 35px;
    text-align: center;
    display: block;
    height: 100%;
    width: 100%;
    font-size: 20px;
    text-decoration: none;
}
#butter-scroll:hover {
    opacity: 1;
}