Great work!

Two things I would consider. One is to add an additional color to your scheme. I notice there is a birght green in your mark, so experiement with a way to incorporate that into the design. (You might also want to play with an orange shade instead.) Also, maybe a subtle drop shadow around the edges?

Secondly, at the bottom of the page, you might want to put the footer inside the "bubble" (so to speak). This would break up the actual page a bit, and give a visual clue that the page is at an end. (Does that make sense?).

It's hard to critique, because it is superbly done. Great job. Now, stop studying and go build it!