JSFiddle - React, Tailwind, and code Playground

HTML

<div id="grid">
    <table width="100%" cellspacing="0" cellpadding="0">
        <tbody>
            <tr class="gridHeader">
                <td>&nbsp;</td>
                <td class="underline">09:00</td>
                <td class="underline">10:00</td>
                <td class="underline">11:00</td>
                <td class="underline">12:00</td>
                <td class="underline">13:00</td>
                <td class="underline">14:00</td>
                <td class="underline">15:00</td>
                <td class="underline">16:00</td>
                <td class="underline">17:00</td>
            </tr>
            <tr id="mon">
                <td class="gridSide">Mon</td>
                <td class="box" id="mon1">&nbsp;</td>
                <td class="box" id="mon2">&nbsp;</td>
                <td class="box" id="mon3">&nbsp;</td>
                <td class="box" id="mon4">&nbsp;</td>
                <td class="box" id="mon5">&nbsp;</td>
                <td class="box" id="mon6">&nbsp;</td>
                <td class="box" id="mon7">&nbsp;</td>
                <td class="box" id="mon8">&nbsp;</td>
                <td class="box" id="mon9">&nbsp;</td>
            </tr>
            <tr id="tue">
                <td class="gridSide">Tue</td>
                <td class="box" id="tue1">&nbsp;</td>
                <td class="box" id="tue2">&nbsp;</td>
                <td class="box" id="tue3">&nbsp;</td>
                <td class="box" id="tue4">&nbsp;</td>
                <td class="box" id="tue5">&nbsp;</td>
                <td class="box" id="tue6">&nbsp;</td>
                <td class="box" id="tue7">&nbsp;</td>
                <td class="box" id="tue8">&nbsp;</td>
                <td class="box" id="tue9">&nbsp;</td>
            </tr>
            <tr id="wed">
                <td class="gridSide">Wed</td>
                <td class="box" id="wed1">&nbsp;</td>
                <td class="box" id="wed2">&nbsp;</td>
                <td class="box" id="wed3">Do all...

CSS

td { padding: 10px; border: 1px solid black}