JSFiddle - React, Tailwind, and code Playground

by Tiago Marinho

HTML

<div class="div1"></div>
<div class="div2"></div>

CSS

*{margin:0;}
div{
    position:absolute;
    width:100%;
    left:0;
}
.div1{
    top:0;
    height:25%;
    background:#f33;
}
.div2{
    top:25%;
    background:#3cf;
    transition:height 1s;
}

JavaScript

function changeHeight(){
        var height = $(".div1").height();
        $(".div2").css({"height":""+ height +""});
    }
window.addEventListener('resize', changeHeight);
changeHeight();