JSFiddle - React, Tailwind, and code Playground
HTML
<div id="background">
<div id="box">
<ol>
<li>asdf asdf asdf</li>
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<li>asdf asdf asdf</li>
<li>asdf asdf asdf</li>
<li>asdf asdf asdf</li>
<li>asdf asdf asdf</li>
<li>asdf asdf asdf</li>
<li>asdf asdf asdf</li>
<li>asdf asdf asdf</li>
<li>asdf asdf asdf</li>
<li>asdf asdf asdf</li>
<li>asdf asdf asdf</li>
<li>asdf asdf asdf</li>
<li>asdf asdf asdf</li>
<li>asdf asdf asdf</li>
<li>asdf asdf asdf</li>
<li>asdf asdf asdf</li>
<li>asdf asdf asdf</li>
<li>asdf asdf asdf</li>
<li>asdf asdf asdf</li>
<li>asdf asdf asdf</li>
<li>asdf asdf asdf</li>
<li>asdf asdf asdf</li>
<li>asdf asdf asdf</li>
<li>asdf asdf asdf</li>
<li>asdf asdf asdf</li>
<li>asdf asdf asdf</li>
<li>asdf asdf asdf</li>
<li>asdf asdf asdf</li>
<li>asdf asdf asdf</li>
<li>asdf asdf asdf</li>
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</ol>
</div>
</div>
CSS
html, body {
height: 100%;
margin: 0px;
}
#background {
display: flex;
align-items: center;
height: 100%;
}
#box {
background-color: yellow;
margin: 0 auto;
width: 200px;
}