JSFiddle - React, Tailwind, and code Playground

HTML

<div class="magic">WOW</div>

CSS

body { background: cyan; }

.magic { background: navy; color: white; width: 200px; height: 50px; line-height: 50px; margin-left: 25px; }
.magic:before {
    content: '';
    color: transparent;
    float: left;
    position: relative; left: -25px;
    width: 0;
    height: 0;
    border-top: 26px solid navy;
    border-left: 26px solid transparent;
    border-bottom: 25px solid navy;
}