JSFiddle - React, Tailwind, and code Playground

HTML

<div id="history_log" class="callout callout medium">

<table class="fixed">


<tbody><tr>
	<td width="10%">  </td>
	<td width="10%">HISTORY</td>
	<td width="20%">Don Pack </td>
	<td width="60%">Customer created Elena Smith. </td>
</tr>


<tr>
	<td width="10%">  </td>
	<td width="10%">HISTORY</td>
	<td width="20%">Don Pack </td>
	<td width="60%">Assignee <span style="text-decoration: underline">SET</span> to Ross Fraiser.  </td>
</tr>

<tr>
	<td width="10%">  </td>
	<td width="10%">HISTORY</td>
	<td width="20%">Nick Duval </td>
	<td width="60%">Facts field changed from None to Functions as Designed (NTF). Facts DATE field changed from  to 02/09/2016.</td>
</tr>


</tbody></table>

		
	
</div>

CSS

<style>
table.fixed {table-layout:fixed;}/*Setting the table width is important!*/
table.fixed td {overflow:hidden;}/*Hide text outside the cell.*/
</style>

JavaScript

$(document).ready(function() {	
$("div:contains('<span style="text-decoration: underline">SET</span> to')").each(function()
{
    var $el = $(this);
    $el.html( $el.html().replace(/<span style="text-decoration: underline">SET</span> to/g, '<span style="text-decoration: underline">SET</span> to') );
});

	
$("div:contains('Changed')").each(function()
{
    var $el = $(this);
    $el.html( $el.html().replace(/Changed/g, '<span style="text-decoration: underline">Changed</span>') );
});


});