JSFiddle - React, Tailwind, and code Playground

HTML

<div>123</div>
<table>
    <thead>
        <tr>
            <th >xyz</th>
        </tr>
    </thead>
    <tbody>
        <tr>
            <td>123</td>
        </tr>
    </tbody>
</table>

CSS

thead,div { border: 5px solid red; }
th {border: 2px}

JavaScript

alert("div border width: " + $('table th').css("border-right-width") + 
      "\r\nthead border width: " + $("thead").css("border-top-width"));
      
$(function() {
    var pressed = false;
    var start = undefined;
    var startX, startWidth;
  
    $("table th").hover(function(e) {
    
        alert($(this).css("innerWidth"))
    });
    
   
});