JSFiddle - React, Tailwind, and code Playground

CSS

</style>

<script src="http://github.hubspot.com/vex/dist/js/vex.combined.js"></script>
<link href="http://github.hubspot.com/vex/dist/css/vex.css" rel="stylesheet" />
<link href="http://github.hubspot.com/vex/dist/css/vex-theme-default.css" rel="stylesheet" />
<style>
.vex-theme-default .title-bar {
    margin: -1em;
    background: #ccc;
    padding: 1em;
    margin-bottom: 1em;
    border-radius: 5px 5px 0 0;
}

.vex-theme-default .title-bar h1 {
    font-size: 1.3em;
    font-weight: normal;
    line-height: 1.2em;
    margin: 0
}

JavaScript

vex.dialog.alert({
    className: 'vex-theme-default',
    unsafeMessage: '<div class="title-bar"><h1>Title</h1></div><p>This is a vex alert with a title.</p>'
});