JSFiddle - React, Tailwind, and code Playground

HTML

<div class ="cover">
  <div >
  </div>   
</div>

CSS

.old{
    position: relative;
}

.cover{
 background-color: blue;   
 background:url(https://www.technogies.com/wp-content/uploads/2018/10/Elderly-At-Using-Technology.jpg) no-repeat;
 background-size:cover;
 width: 100%;
 height: 200vh;
 position: absolute;
 top: 0;
 left: 0;
 z-index: 1;
 opacity: 0.5;
 --filter:blur(10px);
}
.cover div{
  background:blue;
  width:100%;
  opacity:0.5;
  height:100%;
}