.back-top {
    height: 45px;
    width: 45px;
    background: #ff6a00 url("../Images/back-top.png") no-repeat center 50%;
    opacity: 1;
    text-indent: 100%;
    display: inline-block;
    overflow: hidden;
    visibility: hidden;
    white-space: nowrap;
    position: fixed;
    bottom: 25px;
    right: 25px;
    -webkit-border-radius: 50%;
    -moz-border-radius: 50%;
    border-radius: 10px;
    -webkit-transition: opacity 0.3s 0s, visibility 0s 0.3s, background-color 0.3s 0s;
    -moz-transition: opacity 0.3s 0s, visibility 0s 0.3s, background-color 0.3s 0s;
    -o-transition: opacity 0.3s 0s, visibility 0s 0.3s, background-color 0.3s 0s;
    transition: opacity 0.3s 0s, visibility 0s 0.3s, background-color 0.3s 0s;
    z-index: 9999;
}

.back-top.back-top--show,
.back-top.back-top--fade-out,
.back-top:hover {
    -webkit-transition: opacity 0.3s 0s, visibility 0s 0s, background-color 0.3s 0s;
    -moz-transition: opacity 0.3s 0s, visibility 0s 0s, background-color 0.3s 0s;
    -o-transition: opacity 0.3s 0s, visibility 0s 0s, background-color 0.3s 0s;
    transition: opacity 0.3s 0s, visibility 0s 0s, background-color 0.3s 0s;
}

.back-top.back-top--show {
    opacity: 1;
    visibility: visible;
}

.back-top.back-top--fade-out {
    opacity: 0.5;
}

    .back-top:hover {
        background-color: #ff0000;
        opacity: 1;
    }