As a more general-purpose tool, there is also GNU Source-highlight [0] which comes in most distributions. For example to use with less: https://www.gnu.org/software/src-highlite/source-highlight.h...

[0] https://www.gnu.org/software/src-highlite/

In Safari I get "Too Many Requests" error; in Firefox ESR I get a straight "403 Forbidden". What the heck is going on with gnu.org?

Edit, with cURL it's OK… 200.

That makes no sense.