It is not quite clear what you're looking for. It seems you want to apply a different CSS style to the h1 tag of the QA section. By different I mean you want to keep the default to the rest of the site. You can't do that without getting your hands dirty and perform a small core hack. You could do this by means of a theme but it will be a bit more complicated.
So here are the steps to add a CSS class only to that section:
1. Open file qa-include/qa-theme-base.php
2. Perform the changes I've made in this Gist
+ $class = $this->template === 'qa' ? ' class="recent-questions"' : '';
+ $this->output('<h1' . $class . '>');
3. Open file qa-theme/<your-theme>/qa-styles.css and add the style you want to the recent-questions class: