JSFiddle - React, Tailwind, and code Playground
HTML
<div id="div1">div 1</div>
<div id="div2">div 2<br /> next line</div>
CSS
#div1 {float: left; width: 20%; background: red}
#div2 {float: left; width: 80%; background: blue}
JavaScript
$(document).ready(function(){
if($("#div1").height() >= $("#div2").height()){
$("#div2").height( $("#div1").height() );
} else {
$("#div1").height( $("#div2").height() );
}
})