Find the classes in css

-- HikaShop version -- : 4.0.1
-- Joomla version -- : 3.9.1
-- PHP version -- : 7.2

Hello

Where do i find the classes from the email notification , like class="w600" and class="w560" etc ?


defined('_JEXEC') or die('Restricted access');
?><table class="w600" border="0" cellspacing="0" cellpadding="0" width="600" style="margin:0px;font-family: Arial, Helvetica, sans-serif;font-size:12px;line-height:18px;">
<tr>
<td class="w20" width="20"></td>
<td class="w560 pict" style="text-align:left; color:#575757" width="560">
<div id="title" style="font-family: Arial, Helvetica, sans-serif;font-size:12px;line-height:18px;">