#preloader {
    background: #FFF;
    height: 100%;
    position: fixed;
    width: 100%;
    top: 0;
    z-index: 1031;
}

#back-to-top {
    color: #fff;
    position: fixed;
    bottom: 20px;
    right: 20px;
    z-index: 1030;
    height: 50px;
    width: 50px;
    background-repeat: no-repeat;
    background-position: center;
    transition: background-color .1s linear;
    -moz-transition: background-color .1s linear;
    -webkit-transition: background-color .1s linear;
    -o-transition: background-color .1s linear;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    border: #FFF 3px solid;
}