Background image in css file not showing up

[tinar9678]

Hi,

So I'm trying to display an image on my site, but it is not showing up. However, when I just double click on the html file to display the webpage, the picture shows up fine.

I don't understand what the problem is because I have the image file stored inside a folder on the same repository. Not sure if this is a bug or if I'm just missing something.
My website repo:
https://github.com/tinar9678/tinar9678.github.io