CTA button keyboard behaviour should invoke :active style

[jrbarnes9]

When the user selects the CTA link-button with the keyboard (Space key or Enter key), the "pressed" state styled by the :active pseudo-class (shift top, remove `box-shadow) should visible to the user, to provide visibility of the button's state via appropriate feedback.

[willcAND]

The CTA link-button is an <a> element styled like a button, so imitating the behaviour of a key press via the :active pseudo class is not achieved the same way. Requires more investigation. Context - Stack Overflow - How to trigger the :active pseudoclass on keyboard 'enter' press? (using only CSS).