Widget Variations allow for the individual styling of each widget within a position, without it being global. Code wise, this is achieved by adding a class into the module code which loads from the Widget Variation field in the widget settings. The theme CSS adjusts accordingly.

Choose any available suffixes at Appearance → Widgets → Your Widget → Widget Variations

There are 16 suffixes: flag1-3, title1-3, boxleft1-2, boxright1-2, divider, flush, flushtop, flushbottom, noicon & basic.

The Flag adds a solid background image behind the header, in the shape of a flag. The Title suffixes change the styling of the widget titles only. The Box suffixes apply a subtle gradient, in a light or dark shade, to either the left or right side of the widget. Divider simply adds a bevel divider to the bottom of the widget. Remember, you can always combine suffixes together such as flag2 divider, which will produce a colored widget title, with a bottom divider.

Flush will disable all padding and margin to the widget for a tighter fit, with FlushTop and FlushBottom disabling the margin/padding for the Top/Bottom parts of the widget respectively. Noicon removes just the icon, but leaves the gradient with the Basic suffix removing both from the widget styling.