Use :empty pseudo-class select dom in css

:empty pseudo-class selector can used when you need select empty dom in CSS let's show case

<!-- will be selector -->
<div></div>
<div></div>
<div><!-- comment --></div>

<!-- will not selected if has comment with line break  -->
<div>
  <!-- comment here  -->
</div>

<!-- will not be select if contain space -->
<div> </div>

<!-- not be select if contain content-->
<div> anything </div>

<!-- will be selector -->
<div></div>

:empty just used for select DOM which contain nothing even comment.

demo

Hope it can help you :)