Style

The Style layer is concerned with emotion, tone, and visual vocabulary. Because it is the most visible and concrete aspect of an interface, it typically accounts for people’s first impression of a product. Style is influenced by the use of color,the design of icons throughout the interface and the use of typography. Elements of the Style layer also support the Organizational Model in the form of labels, the Viewing and Navigation layer in the form of the names of the input and navigational controls, and the User Assistance layer in the form of alert messages and notifications.

Elements of Style

Colors - Use colors consistently.
Icon design - Icon design and use should be consistent throughout the interface.
Typography - Treat typography with the same care as any other aspect of the visual design.
Animations - Restrain the use of animations to communicate transitions that would otherwise be difficult to discern by the user.