gozden on "WP UI - Tabs, Accordions, Sliders Plugin Tab Title"

Hi everyone,

I am using WP UI plugin for my web site. My problem is that I cannot change tab font size. When I tied to change <h3> tag into <h4>, tab menu was crashed. How can I change the font size of tab title?
Thanks.

<div class="wp-tabs wpui-blue">

	<h3 class="wp-tab-title">Tab1</h3><br>
		<div class="wp-tab-content"> Contents of the nested first tab.
		</div><!-- end div.wp-tab-content -->

	<h3 class="wp-tab-title">Tab2</h3>
		<div class="wp-tab-content">Content of the nested second tab. </div><!-- end div.wp-tab-content -->

</div>