JSFiddle - React, Tailwind, and code Playground

HTML

<div id="a">
    <table id="b">
        <tr><td></td></tr>
    </table>
</div>

CSS

* {
    margin: 0;
    padding: 0;
}

#a {
    background-color: yellow;
}

#b {
    background-color:red;
    height: 50px;
    margin-left: 50px;
    width: -webkit-calc(100% - 50px);
    width: -moz-calc(100% - 50px);
    width: calc(100% - 50px);
}