.back-top
{
    height:52px;
    width:52px;
    background:#cf0000 url("../Images/back-top.png") no-repeat center 50%;
    background:rgba(207,0,0,0.5) url("../Images/back-top.png") no-repeat center 50%;
    opacity:0;
    display:inline-block;
    overflow:hidden;
    visibility:hidden;
    position:fixed;
    bottom:16px;
    right:16px;
    -webkit-border-radius:2px;
    -moz-border-radius:2px;
    border-radius:2px;
    -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;
}
.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:#cf0000;
    opacity:1;
}