ANSWER:

No, this is not negligible.

It’s not permissible to reveal your forehead or any part of your hair. Cover the scarf until your eyebrows. 

I wear a hijab but I also wear glasses, with my glasses there is a small opening between my head and the hijab from my glasses and sometimes a little hair can be visible if you look in. I wear a cap under my hijab but it still ends up showing. Is this negligible?