JSFiddle - React, Tailwind, and code Playground

HTML

<div id="container">
<div id="box1"></div><div id="box2"></div>
</div>

CSS

#container {
background-color: #999;
margin: 0px auto;
width: 1000px;
height: 620px;
z-index: 1;

}
#box1 {
background-color: #0F3;
width: 530px;
height: 75px;
display:inline-block;
z-index: 1;
margin-top: 0px;    
margin-left: 0px;
}
#box2 {
font-size: 0;display:inline-block;
background-color: #00F;
width: 470px;
height: 75px;
z-index: 1;
margin-top: 0px;

}