With in CSS Sculptor, you can select one of the Designs as a starting point, then click the edit button to customize the layout.
The Type tab allows you to edit the fonts and colors used
the Box tab allows you to change the designs box model.
the Design Tab allows you to change the backgrounds and borders.
the print tab allows you to set print CS options for the page.
Similarely in Form builder, you can select a starting design, then click the edit button to edit the forms CSS Settings.