The boundaries of this object are clear. Only the numbers can be ignited and only 7 fireworks can be on screen at any one time. Each explosion fades after a short while. Moving the flame over the Shiseido logo extinguishes the flame, as thus moving it outside the applet's square. Fireworks will only detonate inside the square, no higher. You have no limit of fireworks.
However, moving the cursor over John Maeda's signature yields an interesting result.