JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container body-content">
    <div class="panel panel-default col-md-6">
        <div class="panel-title text-center">Log in</div>
        <div class="panel-body text-center">
             <h6>Use a local account to log in.</h6> 
        </div>
    </div>
</div>

CSS

.panel {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translateX(-50%) translateY(-50%);
}