#scrolltop {
    background: #ccc;
    background-color: rgba(166, 166, 166, 0.2);
    border-radius: 5px;
    cursor: pointer;
    display: flex;
    align-items: center;
    opacity: 0;
    position: fixed;
    text-align: center;
    text-rendering: optimizeLegibility;
    transition: opacity .3s ease-in-out;
    z-index: 7000;
    height: 3rem;
    width: 3rem;
    font-size: 4rem;
    line-height: 1;
    right: 25px;
    bottom: 25px;
    color: #666;
    color: rgba(166, 166, 166, 0.9);
}

#scrolltop:hover{ filter: brightness(108%); }

#scrolltop svg{
    display: inline-block;
    width: 1em;
    height: 1em;
    vertical-align: middle;
    position: relative;
}

@media (min-width: 40em){
    #scrolltop {
        height: 4rem;
        width: 4rem;
    }
}