Default shortcode edit drops feed in WP

I’ve installed the RSS Retriever plugin but have no edit ability to the short code. If I deviate from the default shortcode, with the exception of our website feed URL, the plugin doesn’t show up on my page. How can I make visual edits via CSS too? I’m not finding any CSS files to change the header font to a larger and bolder version and it doesn’t inherent the theme type settings. Our feed is coming from a Blogger Google website, could that be the issue?

The page I need help with: [log in to see the link]