div color overlay css

  background: linear-gradient(#3204fdba, #9907facc), url(https://picsum.photos/1280/853/?random=1) no-repeat top center;

box-shadow: inset 0 0 0 2000px rgb(0 0 0 / 67%);

#hero{
  background-image:url();
  background-size:cover;
  background-position:top center;
  position:relative;
}

#hero::after{
  content:'';
  position:absolute;
  left:0;
  top:0;
  height:100%;
  width:100%;
  background-color:black;
  opacity:0.7;
}