Make site font fancy

[PeterRydberg]

Is your feature request related to a problem? Please describe.
This isn't exactly the most important issue, but I think the site could look a little fancier with some different fonts. Make it 🌟pop🌟. In the titles, especially. The general text looks fine, though, but I went ahead and found an alternative anyway.

Describe the solution you'd like
I think a serif font in the titles could look better, with a sans-serif in the text. Google Fonts has a bunch of different alternatives that can be loaded directly into the browser, so you can try a few different ones.

Describe alternatives you've considered
I tried a few, without overdoing it completely. Playfair Display is a generally lovely font for titles (in graphic design, for instance), but I was unsure how it would look in a browser. I think it looks fairly good compared to some others I tried, but it's not perfect (numbers should be equal size to letters for subject codes imo). I used Railway for the general text, which is pretty crisp and nice. I'm sure you can find better though, I didn't look to hard. Also, legibility is always prioritised!

Also, I wouldn't complain if you used the OWF font scheme! That one looks good :)

Additional context
Example (using the CSS from #71):