JSFiddle - React, Tailwind, and code Playground

HTML

<h1>table 2 </h1>

<table style="width:300px" class="tabx">
    <tr>
        <td>Jill</td>
        <td>Smith</td>
        <td>50</td>
    </tr>
    <tr>
        <td>Eve</td>
        <td>Jackson</td>
        <td>94</td>
    </tr>
</table>

<h1>table 2 </h1>

<table style="width:300px" class="tabx">
    <tr>
        <td>Jill</td>
        <td>Smith</td>
        <td>50</td>
    </tr>
    <tr>
        <td>Eve</td>
        <td>Jackson</td>
        <td>94</td>
    </tr>
</table>

JavaScript

var t1 = document.getElementsByClassName("tabx");
    
for(index = 0; index < t1.length; ++index)
{
        var Ri = t1[index].getElementsByTagName("tr");
        var Ca = t1[index].getElementsByTagName("td");
        var nRi = Ri.length;
        var nCa = Ca.length;
        var nCo = nCa / nRi;
        for (var i = 0; i < nCo; i++) {
            Ca[i].style.backgroundColor = "rgb(221,247,255)";
        }
        for (var i = nCo; i < nCa; i = i + nCo) {
            Ca[i].style.backgroundColor = "rgb(221,247,255)";
        }
}