JSFiddle - React, Tailwind, and code Playground

HTML

<div>
<div id="overlay-modal>
          <div class="inner-modal">
            <p>Content in here</p>
          </div>
  </div>
</div>

CSS

#overlay-modal
    			{
    				position:absolute;
    				top:0;
    				left:0;
    				width:100%;
    				height:100%;
    				background-color:black;
    				filter: alpha(opacity=80);
    						opacity: 0.8; 
    				z-index:999;
    			}
    			.inner-modal
    	        {
    	            width: 400px;
    	            height: 270px;
    	            margin: 200px auto;
    	            background-color: white;
    	        }