page::before{
content: '';
position: fixed;
top: 0;
z-index: -1;
width: 100vw;
height: 100vh;
background: url("") no-repeat center/cover;
}
page::after{
content: '';
position: fixed;
top: 0;
z-index: -1;
width: 100vw;
height: 100vh;
background:rgba(0,0,0,.5);
}