.cd-top {
    display: block;
    background-color: #b70120;
    color: #fff;
    cursor: pointer;
    position: fixed;
    bottom: 45px;
    right: 15px;
    z-index: 999999;
    overflow: hidden;
    visibility: hidden;
    opacity: 1;
    padding: 13px;
    font-size: 1.5em;
    border-radius: 100%;
    box-shadow: none;
    opacity: 0;
    -webkit-transition: opacity .3s 0s, visibility 0s .3s, background-color .3s 0s;
    transition: opacity .3s 0s, visibility 0s .3s, background-color .3s 0s;
}

    .cd-top > i {
        display: block;
        width: 1em;
        height: 1em;
    }

    .cd-top.cd-top--show,
    .cd-top.cd-top--fade-out,
    .cd-top:hover {
        -webkit-transition: opacity .3s 0s, visibility 0s 0s, background-color .3s 0s;
        transition: opacity .3s 0s, visibility 0s 0s, background-color .3s 0s;
    }

    .cd-top.cd-top--show {
        /* the button becomes visible */
        visibility: visible;
        opacity: 1;
    }

    .cd-top.cd-top--fade-out {
        /* if the user keeps scrolling down, the button is out of focus and becomes less visible */
        opacity: .5;
    }

    .cd-top:hover {
        background-color: #e86256;
        opacity: 1;
    }

@media only screen and (min-width: 768px) {
    .cd-top {
        right: 20px;
        bottom: 20px;
    }
}

@media only screen and (min-width: 1024px) {
    .cd-top {
        height: 50px;
        width: 50px;
        right: 30px;
        bottom: 30px;
    }
}