JSFiddle - React, Tailwind, and code Playground

HTML

<div id="top-element">Some div that has greater width than the inner div</div>
<div id="iframe-wrapper">
    <iframe src="http://www.apple.com/" scrolling="auto"></iframe>
</div>

CSS

html {
    display:table;
    height:100%;
    width:100%;
}
body {
    display:table-cell;
    vertical-align:middle;
}
#top-element {
    position:absolute;
    top:0;
    left:0;
    background:orange;
    width:100%;
}
#iframe-wrapper {
    text-align:center;
}