Product Landing Page Navbar Error

Tell us what’s happening:
If my navbar is fixed at the top of page when i scroll it stays at the top why am i getting an error message stating:
navbar should always be at the top of viewport

Please take a look at my link

Your code so far

Your browser information:

User Agent is: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/66.0.3359.170 Safari/537.36 OPR/53.0.2907.68.

Link to the challenge: