Need help with styling

I agree, the styling documentation seems lacking. If you want it to look like Definition you can try the following:

Go to the Definition demo and right click on the page. Select View Frame Source. Look for the links wp-content/themes/definition/style.css and layout.css.

Right click each one and “open in new tab” or “window” you can then do a search for the keyword “testimonial” in each of those stylesheets to find reference to how their testimonials were styled on that theme.

I believe they use the Testimonials plugin in their themes now so the css structure for the shortcode/widgets should follow mostly the same class’s/id’s that they use.