Fix/more css fixes and stuff

Fixes #77 (closed) #74 (closed)

Changed usercard layout around a bit. Removed scary unnecessary (negative) margins (if you know why they were there - please tell me). Made entire area around user-counters clickable instead of just link + added hover background and selected background - this way "Statuses" is highlighted initially when opening user profile - this should hint user that you can switch views. This change however forced me to move average per day counter somewhere else - it eats up vertical space in "statuses" counter and creates inconsistency - "followers" and "following" counters end up having huge empty space below.

I added some text-shadow-based text outline for text in usercard, so it will increase text readability over light (esp. white) backgrounds. Such text-shadow is atrocious code-wise (basically several non-blurred shadows on top of each other) so it's moved away into variables.

Changed lightFg to be much more intense than it is now (mod * 5) and used it in usercard for text color, including the small text (for better readability), as far as I could see lightFg is barely used anywhere. Added semi-transparent (50%, should be enough for white-on-white and black-on-black cases) bg overlay over profile cover art, removed the outlines mentioned in strike-through text above. Because of white-on-white (light theme + white user art) and black-on-black cases it's impossible to highlight "current tab" in profile view, so i used simple thicc link-colored underline (border-bottom) instead. Examples comparing this variation with previous are here