Well done! I especially like the font-family you used here.
I think you can imporve 2 things.
You are already chaning the look for cursor on mousehover on nav links but you can also change their colors on hover in addition.
Display of your codes. I would do unindent them and shift them to the left. You will need to tweak your htmls for that and shift them to the left. It will also help If you give pre tags no max-width property.