#back-to-top {
    display: inline-block;
    background-color: var(--colore-accento);
    width: 50px;
    height: 50px;
    text-align: center;
    border-radius: 100rem;
    position: fixed;
    bottom: 30px;
    right: 30px;
    -webkit-transition: background-color .3s, opacity .5s, visibility .5s;
    -o-transition: background-color .3s, opacity .5s, visibility .5s;
    transition: background-color .3s, opacity .5s, visibility .5s;
    opacity: 0;
    visibility: hidden;
    z-index: 9999996;
}
#back-to-top:after {
    content: "\f106";
    font-family: "Font Awesome 5 Free";
    font-weight: 900;
    font-size: 1.5rem;
    line-height: 50px;
    color: #fff;
}
#back-to-top.show {
    opacity: 1;
    visibility: visible;
    cursor:pointer;
}
#back-to-top.show:hover,
#back-to-top.show:focus
{
    text-decoration: none;
}
#back-to-top svg{
    position: absolute;
    top: 50%;
    left: 50%;
    width: 90%;
    height: 90%;
    stroke: white;
    -webkit-transform-origin: 50% 50%;
    -ms-transform-origin: 50% 50%;
    transform-origin: 50% 50%;
    -webkit-transform: translate(-50%,-50%) rotate(-90deg) ;
    -ms-transform: translate(-50%,-50%) rotate(-90deg) ;
    transform: translate(-50%,-50%) rotate(-90deg) ;
    -webkit-transition: stroke-dashoffset .2s;
    -o-transition: stroke-dashoffset .2s;
    transition: stroke-dashoffset .2s;
}