Strange enough, for Chrome the number that indicates the actual amount of mana you have is located to the right of where it should be. Where it should be can be found by playing it on Firefox and possibly Internet Explorer. And where that actually is is right next to the mana bar.
The concept is great. Usually for this type of strategy game, it's just amassing units and conquering the most bases. The ranking/leveling system changes the gameplay and really makes it stand out as an awesome game.
The only bad thing about this game is that it auto-completes the puzzle when you don't want it to, but its a great game. And regarding colors, black is the presence of all colors and white is the absence of all colors in paint which in this game you use paint, not light.