JSFiddle - React, Tailwind, and code Playground

HTML

<div class="DivHolder">
   <div class="DivLeft"></div>
   <div class="DivRight"></div>
</div>

CSS

.DivLeft {
    height:241px;
    width:200px;
    background:#000;
    float:left;
}
.DivRight {
    height:720px;
    width:200px;
    background:#000;
    float:right;
}

JavaScript

setTimeout(function(){
    $(".DivLeft").css('min-height', $(".DivRight").height());
},5000);