adding overlay to image css code example

Example 1: How to overlay image with color in CSS?

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

Example 2: overlay a box in css

html, body {
  min-height: 100%;
}

body {
  position: relative; /* needed if you position the pseudo-element absolutely */
}

body:after {
  content: "";
  display: block;
  position: fixed; /* could also be absolute */ 
  top: 0;
  left: 0;
  height: 100%;
  width: 100%;
  z-index: 10;
  background-color: rgba(0,0,0,0.2);
}