#back_top {
    bottom: 10px;
    cursor: pointer;
    display: none;
    padding: 4px;
    position: fixed;
    right: 0px;
    bottom: 0px;
    text-align: center;
    transition: all 0.3s ease-out 0s;
    -webkit-transition: all 0.3s ease-out 0s;
    -moz-transition: all 0.3s ease-out 0s;
    z-index: 9998;
}

#back_top span {
    border-radius: 50%;
    box-shadow: 0 0 0 4px #62BDFE;
    -webkit-box-shadow: 0 0 0 4px #62BDFE;
    -moz-box-shadow: 0 0 0 4px #62BDFE;
    color: #62BDFE;
    display: inline-block;
    float: left;
    height: 40px;
    line-height: 40px;
    margin: 0 10px 10px 0;
    padding-top: 6px;
    position: relative;
    text-align: center;
    transition: color 0.3s ease 0s;
    -webkit-transition: color 0.3s ease 0s;
    -moz-transition: color 0.3s ease 0s;
    width: 40px;
    z-index: 1;
}

#back_top span:after {
    background: none repeat scroll 0 0 #62BDFE;
    border-radius: 100%;
    -webkit-border-radius: 100%;
    -moz-border-radius: 100%;
    box-sizing: content-box;
    content: "";
    height: 100%;
    left: -2px;
    padding: 2px;
    pointer-events: none;
    position: absolute;
    top: -2px;
    transition: transform 0.2s ease 0s, opacity 0.3s ease 0s;
    -webkit-transition: -webkit-transform 0.2s ease 0s, opacity 0.3s ease 0s;
    -moz-transition: -moz-transform 0.2s ease 0s, opacity 0.3s ease 0s;
    width: 100%;
    z-index: -1;
}

#back_top:hover span:after {
    opacity: 0;
    transform: scale(1.5);
    -webkit-transform: scale(1.5);
    -moz-transform: scale(1.5);
}

#back_top i {
    font-size: 35px;
    color: #fff;
    vertical-align: top;
    line-height: 25px;
    transition-duration: 0.3s;
    -webkit-transition-duration: 0.3s;
    -moz-transition-duration: 0.3s;
}

#back_top:hover i {
    color: #62BDFE;
}