JSFiddle - React, Tailwind, and code Playground

HTML

<div class="balao">Ola!</div>

CSS

.balao {
    float:left;/* ou float:left, vai do seu uso */
    color:#fff;
    background-color:#37688D;
    border-top:10px solid #37688D;
    border-left:10px solid transparent;
    background-clip: padding-box;
    padding: 0 10px 10px 10px;
}