JSFiddle - React, Tailwind, and code Playground

HTML

<label>A</label><br/>
<label>B</label><br/>
<label>C</label><br/>
<label>D</label><br/>
<label>E</label><br/>
<label>F</label><br/>
<label>R6a</label>

CSS

label
{
    background-color:Black;
    color:White;
    padding:1px;
    font-family:sans-serif;
    text-align:center;
    vertical-align:middle;
    display:inline-block;
}

JavaScript

$(document).ready
(
    function()
    {
        $('label').each(function() {$(this).css('min-width', $(this).css('height'));});
    }
);