JSFiddle - React, Tailwind, and code Playground

HTML

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html>
    <head>
    </head>
    <body>
        <table>
            <thead>
                <tr>
                    <th>Table head th</th>
                    <td>Table head td</td>
                    <td>Table head td</td>
                </tr>
            </thead>
            <tbody>
                <tr>
                    <th>Table body th</th>
                    <td>Table body td<br/>Table body td</td>
                    <td>Table body td</td>
                </tr>
                <tr>
                    <th>Table body th</th>
                    <td>Table body td</td>
                    <td>Table body td</td>
                </tr>
            </tbody>
        </table>
    </body>
</html>

CSS

th, td {
    width: 100px;
    position: relative;
    vertical-align: top;
}
th:after,
td:after {
    content: ".";
    font-size: 8px;
    line-height: 2px;
    text-indent: -10px;
    background: red;
    width: 100%;
    height 2px;
    position: absolute;
    bottom: 0px;
    left: 0;
    overflow: hidden;
}
th {background: yellow;}
td {background: pink;}