There are 8 stylistic widget variations which provide a unique style variation to the widget: title1-4 and box1-4. There are also rt-basic and rt-bevel variations; and various additional structural variations, these affect the layout and metrics of the widget.
Furthermore, you can also add FontAwesome icons into the Custom Variations. You will get a medium sized icon to the left of the title. Suffixes are in the icon-NAME format such as icon-star, as shown on the Typography page.