JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
    <div class="content">
        <h1>Conteúdo</h1>
        <p>Subtítulo</p>
    </div>
</div>

CSS

.container {
    position: absolute;
    width: 100%;
    height: 100%;
    background: #ccc;
}

.content {
    position: absolute;
    text-align: center;
    top: 0;
    bottom: 0;
    left: 0;
    right: 0;
    width: 50%;
    height: 50%;
    margin: auto;   
    background: #eee;
}