JSFiddle - React, Tailwind, and code Playground

HTML

<table id="table">
    <tr>
        <th></th>
        <th></th>
        <th></th>
        <th></th>
        <th colspan="2"></th>
    </tr>
    <tr>
        <td rowspan="3"></td>
        <td></td>
        <td></td>
        <td rowspan="2" colspan="2"></td>
        <td></td>
    </tr>
    <tr>
        <td></td>
        <td></td>
        <td></td>
    </tr>
    <tr>
        <td></td>
        <td></td>
        <td></td>
        <td></td>
        <td></td>
    </tr>
</table>

CSS

table { border-collapse: collapse; position: absolute; top: 0px; left: 0px; }
td, th { width: 1px; height: 1px; padding: 0px; background: red; }

JavaScript

var tableGrid = {
        
    check: function( pos ) {
        try {
           
            var x = pos.col - 1;
            var y = pos.row - 1;
            return document.elementFromPoint( x, y );

        } catch(e){ return null; }
    }
};

tableGrid.check( { row: 3, col: 5 } ).style.background = "#000";