JSFiddle - React, Tailwind, and code Playground

HTML

<div class="parentDiv">
  <div class="childDiv">
    
  </div>
</div>

CSS

div.parentDiv { position:relative; background-color:#333; padding:0; margin:20px; float:left; }

div.parentDiv:before { content:""; display:block; padding:5px; background-color:#f60; border:2px solid white; position: absolute; top:-2px; right:-2px; border-bottom-left-radius: 10px; cursor:pointer}

div.childDiv{padding:20px; margin:0}

JavaScript

jQuery(document).ready(function($){
	$('div.parentDiv').click(function(e){
    if( $(e.target).closest('.childDiv').length==0 ){
      //so clicked on psudo :before!
      //do your work ;)
			alert('Psudo :before element is clicked!');
    }
  });
});