html - Basic CSS - how to overlay a DIV with semi-transparent DIV on top

Question

I'm struggling to make this render right in my browser (Chrome). I have a wrapper holding all the elements of the HTML, and I want to have a DIV (lets call it div-1) that hold a image, and has a overlay div on top of it to the left, like I sketched in this picture...any quick solutions?

Answer 1

Here's a pure CSS solution, similar to DarkBee's answer, but without the need for an extra .wrapper div:

.dimmed {
  position: relative;
}

.dimmed:after {
  content: " ";
  z-index: 10;
  display: block;
  position: absolute;
  height: 100%;
  top: 0;
  left: 0;
  right: 0;
  background: rgba(0, 0, 0, 0.5);
}

I'm using rgba here, but of course you can use other transparency methods if you like.