JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
    <div class="vertical-center">
        <div class="offset">
            <h1>Hiya</h1>
            <p>I'm a paragraph.</p>
        </div>
    </div>
</div>

CSS

.container {
    position:relative;
    width:500px;
    height:200px;
    border:1px solid black;
}
.vertical-center {
    position:absolute;
    height:40px;
    left:0px;
    top:50%;
    border:1px solid blue;
}
.offset {
    position:relative;
    margin-top:-100px;
}