Introduce Continue Button states in adherance to the design file specifications

[jarolrod]

We are missing some states for the continue button which are defined in the design file:

default (implemented)	Hover	Pressed	Focused

#214 would handle the Focused state.

[jarolrod]

@GBKS are there any specifications for animation between states?

[GBKS]

For buttons, I usually put a 150ms transition duration. For text-based ones 100ms. Maybe start with those and see how it feels? Should be snappy enough so it feels really responsive, but still smooth (meaning not abrupt).