//body样式
body.model{
    background-color: #263238;
    color: #aaa;
}
//class 样式
body.model .footer {
 
    color: #aaa;

body {background-image: url("https://img2020.cnblogs.com/blog/2025976/202005/2025976-20200502173357303-1729189419.png");}