How do I change the style on the active tab?

I've installed a Wordpress plugin that creates jquery tabs on the page.

I am now trying to change the style of the active tab so it stands out. (see attached)

The page code:

<div id="content-page" class="span9 content group">
<div id="post-6130" class="post-6130 page type-page status-publish hentry group">
<div class="responsive-tabs">

<h2 class="tabtitle">TAB 1</h2>
<div class="tabcontent">
CONTENT FOR TAB 1<br/>
</div>
<h2 class="tabtitle">TAB 2</h2>
<div class="tabcontent">
CONTENT FOR TAB 2<br/>
</div>
<h2 class="tabtitle">TAB 3</h2>
<div class="tabcontent">
CONTENT FOR TAB 3</p>
</div></div>
</div>

The css is attached as well as a screenshot of what I am trying to do. Any help is greatly appreciated.
tabby.css
tabs.png