This topic to suggest the update and the correction of the simplicity theme for several reasons:
1/ removing the "margin: 0" attribute for tables in the style. I had to remove manually in order to be able to customize the border of my tables.
2/ submenus on the right handside
4/ dropdown menus
You could make to different versions available: one with dropdown menus, and one without dropdown menus as it is now.
An update like this could help prevent future questions on the aspects listed above.
Thank you for reading me.