CSS Stylesheet not being Applied


I don't think the CSS stylesheet is getting picked up or applied properly and when using a browser inspector it says whatever styling there is, is on line 1 of the stylesheet.

I'm using Firefox, it is up-to-date, the cache has been cleared and my computers been restarted.

Some styling must be being applied because the width of the content has been restrained and centered.

Any ideas?
Thanks for your time!