How to show descriptions when a user hovers over a form element
The entire tooltip code is found within the Rubik theme in the files core.css and core-rtl.css.  The majority is within core.css.  The specific piece that shows the tooltip is:

.page-content .form-item:hover &gt; .description { display:block; }


But each tooltip has text contained in &lt;div class='description'&gt;&lt;/div&gt;, so you can search through core.css/core-rtl.css and find statements regarding .description