Responsive portfolio site using only html and css

So i just finished this project and yet again i had a couple of difficulties and there are some "errors" too. So:

1. the footer doesn't want to go all the way down (you can see the diffence in the color, the grey one is the footer).
2. the whole hover on the project thing i'm not sure if i did it correctly or if there is a better and faster way (you can also see that the hover "shadow" "overflows" on the top and bottom side of the project image)
3. the background decoration and profile picture i'm not sure again if i did it right, especially with the responsiveness of profile picture
4. im having a hard time to position the nav bars (top and bottom)

And that's it I think. If you see anything else that's wrong please feel free to correct me. I'd help me a lot. Thank you!