JSFiddle - React, Tailwind, and code Playground

HTML

<div id="container">
       <div id="first">Hello World</div>
       <div id="second">I want to be at the top</div>
    </div>

CSS

#container {
    float:left;
    width:100%;
}

#first {
    float:left;
    width:100%;
    background:lightblue;
    height:200px;
}

#second {
    float:left;
    height:200px;
    width:100%;
    background:yellow;
}