-Styles must be improved (full width for smartphones, selectable text for PGN...)
-Tooltip text should fade (even when mouse stay on it, especially for small screens)
-Checkered stage 2: switch button at reserve position.
-If a played disconnect right after opponent sent a move, it might be never received: secure this
-Think about non-conventional variants with 2 kings for example: undercheck highlight?
- --> underCheck should return a vector in this case. Adapt.
+styling: connection indicator, names, put movesList + chat in better positions
+complete translations, stylesheets, variants rules ...