/* 将background-image中url改成自己gif的路径即可，loading的样式 */
.preloader {
    position: fixed;
    left: 0px;
    top: 0px;
    height: 100%;
    width: 100%;
    z-index: 99999;
    background-color: #ffffff;
    background-position: center center;
    background-repeat: no-repeat;
    background-image: url(https://static.igem.wiki/teams/4703/wiki/loading.gif);
}