see text though the overlay div element

I have 2 div elements with background-color set overlaying on top of another div with content. In case-1 overlay is not a sibling of the content div so it allow background text to be visible to user.
In case-2 the overlay is a sibling of the content div so it is not showing the text to user.

Case-1

<div class="overlay"></div>
<div class="example-container">
  <div class="child1">
    Case 1 - Sample Text 1
  </div>
</div>

Case-2

<div class="child1">
  Case 2 - Sample text 2
</div>
 <div class="overlay">
 </div>

Sample JSfiddle to simulate 2 scenarios.

Any idea why this behavior in html? How could we make the overlay div with background color (case-2) always allow text transparency.

>Solution :

The issue here is that the div is being rendered over the text. This can be fixed easily by giving the overlay a z-index property of -1. This makes the div render under the text, allowing you to see it.

example overlay css

.overlay {
    position: absolute; 
    background-color: gray;
    top:0;
    left:0;
    width: 100px;
    height: 100px;
    z-index: -1;
  }

Alternatively since you want it to overlay (if you actually don’t that is a very misleading name) just set the opacity lower

.overlay {
    position: absolute; 
    background-color: gray;
    top:0;
    left:0;
    width: 100px;
    height: 100px;
    opacity: 0.5;
  }