/* 页面全局背景 */
body {
    background: url("gb.jpg") center/cover no-repeat fixed;
    margin: 0;
}

/* 1~15 包裹容器内的超链接 */
.link-group a {
    background: url("gb.JPG") center/100%100% no-repeat;
    display: inline-block;
    padding: 5px 9px;
    margin: 5px;
    color: white;
    text-decoration: none;
}
.link-group a:hover {
    opacity: 0.8;
}