JSFiddle - React, Tailwind, and code Playground

HTML

<div id='container'>
    <div id='content'>
        Content<br>Content<br>Content<br>Content<br>Content<br>Content<br>
    </div>
    <div id='sidebar'>
        Sidebar<br>Sidebar<br>Sidebar
    </div>
</div>

CSS

body{
    background:#eee;
}
#container{
    width:500px;
    height:auto;
    float:left;
}
#content{
    width:300px;
    float:left;
    background:#fff;
}
#sidebar{
    width:150px;
    float:right;
    background:#fff;
   
}

JavaScript

var cHeight = $('#content').css('height');
$("#sidebar").css('height',cHeight);
console.log($("#sidebar").css("height"));