JSFiddle - React, Tailwind, and code Playground

HTML

<div style="display:flex; width: 400px">
    <div id="a">a</div>
    <div id="b">b</div>
    <div id="c">c</div>
    <div id="d">d</div>
</div>

CSS

div div {
    flex: 1 1 33%;
    border:1px solid black;
    box-sizing: border-box;
}

#a {
    padding-right: 100px;
}

#d {
    flex-basis: 200px;
    width: 200px;
}