Does anyone recognize this format?

[helios]

https://github.com/Helios-vmg/ONSlaught/tree/master/trunk/doc/NScrAPI

I'm 80% I used to open this with a browser, but none of them work nowadays, so maybe I'm wrong. Is there some software out there that can display XMLs with CSS sort like they were were HTMLs?

[Null]

Works fine, as long as files are served via http server -- https://imgur.com/a/WZBoBlt

[helios]

Huh. I'll have to try that later.