JSFiddle - React, Tailwind, and code Playground

HTML

<div style="display:flex">
    <div id="a">a</div>
    <div id="b">b</div>
    <div id="c">c</div>
</div>

CSS

div div {
    flex: 1 1 0;
    border:1px solid black;
    box-sizing: border-box;
}

#a {
    padding-right: 50px;
}