JSFiddle - React, Tailwind, and code Playground

HTML

<div class="btn"><div class="txt"></div></div>

CSS

.btn {
    padding: 0px;
    border: 1px solid red;
    display: inline-block;
}

.txt {
    display: inline-block;
    -font-size: 12px;
    -line-height: 10px;
    width: 12px;
    height: 12px;
    border: none;
    padding: 0;
    margin: 0;
    background: #77FF77;
}