JSFiddle - React, Tailwind, and code Playground

HTML

<div class="divClass">
    <form id="frm" method="post" action="/NotDefinedYet/index.xhtml" class="frmClass">
        <input type="text" name="j_idt9:j_idt10:Username" placeholder="Username">
    </form>
</div>

CSS

.divClass{
        position: relative;
        background-color: grey;
        width: 350px;
        height: 450px;
    }
    .frmClass{
        background-color: white;
        position: absolute;        
        top: 50%;
        left: 50%;
        margin-top: -75px;
        margin-left: -140px;
        width: 280px;
        height: 150px;
    }