body{
    background-image: url(https://images.cnblogs.com/cnblogs_com/blogs/814796/galleries/2401725/o_240601081914_IMG_20240601_161425.jpg);
    background-repeat: no-repeat;
    background-position: center;
    background-attachment: fixed;
}
#home{
    opacity: 0.9;
}
.navbar{
    position:fixed;
    top:0;
    left:0;
    width: 100%;
    z-index: 999;
}