JSFiddle - React, Tailwind, and code Playground

HTML

<div id="bg-right"></div>
<div id="content">
<!-- only need #content for the example, works without it -->
<p>Lorem ipsum…</p>
<p>Lorem ipsum…</p>
<p>Lorem ipsum…</p>
<p>Lorem ipsum…</p>
<p>Lorem ipsum…</p>
<p>Lorem ipsum…</p>
<p>Lorem ipsum…</p>
<p>Lorem ipsum…</p>
<p>Lorem ipsum…</p>
<p>Lorem ipsum…</p>
<p>Lorem ipsum…</p>
<p>Lorem ipsum…</p>
<p>Lorem ipsum…</p>
<p>Lorem ipsum…</p>
<p>Lorem ipsum…</p>
<p>Lorem ipsum…</p>
<p>Lorem ipsum…</p>
<p>Lorem ipsum…</p>
<p>Lorem ipsum…</p>
<p>Lorem ipsum…</p>
<p>Lorem ipsum…</p>
<p>Lorem ipsum…</p>
<p>Lorem ipsum…</p>
<p>Lorem ipsum…</p>
<p>Lorem ipsum…</p>
<p>Lorem ipsum…</p>
<p>Lorem ipsum…</p>
<p>Lorem ipsum…</p>
<p>Lorem ipsum…</p>
<p>Lorem ipsum…</p>
<p>Lorem ipsum…</p>
<p>Lorem ipsum…</p>
<p>Lorem ipsum…</p>
<p>Lorem ipsum…</p>
<p>Lorem ipsum…</p>
<p>Lorem ipsum…</p>
</div>

CSS

body {
    background-color: purple;
}
#bg-right {
    background-color: yellow;
    position: fixed;
    top: 0;
    bottom: 0;
    left: 50%;
    right: 0;
    z-index: -1;
}

#content {
    margin: 1em;
    background: white;
}