All Widgets Should be Styled Correctly

My WordPress theme was soft-rejected. Once of the reason was below:

Please ensure sure all default WordPress widgets are styled and display properly in all widgetized areas. You can check with the Monster Widget WordPress plugin [Monster Widget – WordPress plugin | WordPress.org].

The screenshot the reviewer mentioned is of a widget that is actually styled correctly (in netsted fashion). So, I’m not sure what the reviewer wants here actually.

Any help would be appreciated.