Lichess LIFBA Theme per xlassmgreat

Adds basic, yet very cool animations and borders to your Lichess board. When you go to any board in lichess.org, you'll find that your last moves, premoves and checks are highlighted in a much more fancy way, including background animations. Also adds a cool opacity animation (where the piece slowly becomes visible)

Source code: https://github.com/xlassmgreat/lichess_lifba_theme