Add small Login button and Signup link on mobile

[adriaandotcom]

@amritnagi: login link??? 😁 How about having sign-up as a text link left to a red login button?

• [x] Add login button on mobile and desktop
• [x] Replace signup button with "Sign up" link left to the Login button

[jibsaramnim]

Fixed in the new-header branch, pending deployment!