JSFiddle - React, Tailwind, and code Playground

HTML

<table>
    <thead>
        <tr>
            <td></td>
            <td>Name</td>
            <td>Last</td>
            <td>DOB</td>
        </tr>
    </thead>
    <tbody>
        <tr>
            <td><input type=checkbox /></td>
            <td>Blah</td>
            <td>Blah</td>
            <td>1/1/11</td>
        </tr>
        <tr>
            <td><input type=checkbox /></td>
            <td>Blah</td>
            <td>Blah</td>
            <td>1/1/11</td>
        </tr>
        <tr>
            <td><input type=checkbox /></td>
            <td>Blah</td>
            <td>Blah</td>
            <td>1/1/11</td>
        </tr>
        <tr>
            <td><input type=checkbox /></td>
            <td>Blah</td>
            <td>Blah</td>
            <td>1/1/11</td>
        </tr>
        <tr>
            <td><input type=checkbox /></td>
            <td>Blah</td>
            <td>Blah</td>
            <td>1/1/11</td>
        </tr>
        <tr>
            <td><input type=checkbox /></td>
            <td>Blah</td>
            <td>Blah</td>
            <td>1/1/11</td>
        </tr>
        <tr>
            <td><input type=checkbox /></td>
            <td>Blah</td>
            <td>Blah</td>
            <td>1/1/11</td>
        </tr>
        <tr>
            <td><input type=checkbox /></td>
            <td>Blah</td>
            <td>Blah</td>
            <td>1/1/11</td>
        </tr>
        <tr>
            <td><input type=checkbox /></td>
            <td>Blah</td>
            <td>Blah</td>
            <td>1/1/11</td>
        </tr>
        <tr>
            <td><input type=checkbox /></td>
            <td>Blah</td>
            <td>Blah</td>
            <td>1/1/11</td>
        </tr>
    </tbody>
</table>

CSS

table {
    border-collapse: collapse;
}
table td {
    border: 1px solid black;
    padding: 5px;
}

JavaScript

$(function() {
    var $table = $("table");
    var $tbody = $table.find("tbody");
    var offset = $tbody.offset();
    var height = offset.top;
    $table.find("tbody tr").each(function() {
        var trHeight = $(this).outerHeight();
        createMarker(trHeight);
        height += trHeight;
    });
    
    function createMarker(h) {
        var $marker = $("<div/>", {
            css: {
                position: "absolute",
                top: height + "px",
                height: h + "px",
                width: "25px",
                "background-color": "red",
                "border": "1px solid blue"
            }
        });
        $("body").append($marker);
    }
});