I have wondered many times.
Of course I can always use a browser but it’s overkill.
The same goes for yad or zenity, they pull in webkit which is a full-fledged browser engine, and at least yad does not have an offline mode.
I just want to look at some local HTML (incl. images) & CSS styling.
+1 for Dillo. Yes, it’s limited, it’s largely abandoned for the past 10 years and you won’t run web apps on it. But it is indeed blazingly fast and very low on resources, like OP requested. I didn’t know NetSurt, thanks for that!