.arrow-to-top{
    position: fixed;
    bottom: 15px;
    right: 15px;
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    -webkit-transition: all .4s;
    -moz-transition: all .4s;
    -ms-transition: all .4s;
    -o-transition: all .4s;
    transition: all .4s;
    z-index: -10000;
}

.arrow-to-top.show{
    opacity: 1;
    z-index: 1000;
    visibility: visible;
}