Square_side = math.min(App.screen.width/5, App.screen.height/5, 100)

	local w, h = App.screen.width/5, App.screen.height/5
	if OS == 'iOS' or OS == 'Android' then
		-- make space for the pop-up keyboard
		h = h/2
	end
	Square_side = math.min(w, h, 100)