Switch global font to Computer Modern

[jengelh]

A sample PR for employing the same font in the HTML as is used in the PDF. There is a bit of concern though: Serif fonts and low-resolution (96dpi) displays don't historically mix well, which is why you don't see them all that often on webpages (e.g. newspaper sites). It's ok when you look at it with a mobile phone (just tested at 400dpi) or set browser page magnification to 150% on a low-dpi screen, so 🤷 goodenoughforme.

Fixes #98 .

Fixes #103 (no longer using font fragments with unicode-range).

Incidentally, this also fixes contacting Google services (GDPR and all that).

Haven't looked at the MathJAX parts at all(!), I just made sure the new CSS renders ok with https://eel.is/c++draft/format.string.escaped#example-1 .

[Eelis]

This reduces the load time of /full on my machine from almost 3 minutes, to about 10 seconds, which is awesome!

But it doesn't solve the wideness and header overflow issue mentioned in #98, because it changes from the status quo:

to:

(In the PDF it looks like:)

[jengelh]

overflow behavior is a separate topic to look at