-End of game a bit too verbose: should just say "Black win" ... + show PGN
-Styles must be improved (full width for smartphones, selectable text for PGN...)
+Finish rules translation in Spanish + improve existing ones
+Design: final touch (gain extra space on top, using space on the right)
+Crazyhouse: center reserves, grey if zero available, numbers superimposed
+Promotions: increase pieces sizes, better background.
+Code: use two spaces instead of tabs, everywhere.