hi fairy! i presume you have been successful in getting hugo to work with devuan chimera? if not, i can give it try it on my new setup - i’m an archlinux user, but i just installed peppermint on an old i686 laptop with devuan chimera.
as far as, hugo and css, @antoinentl has explained the difference. if you write html from scratch (probably the way w3school is showing you), then you don’t use hugo, which uses markdown (or orgmode) and then generates the html for you.
you can then use a theme to get it looking nice:
Hugo Themes
if you want to fine tune things, then you can add css style sheets - something i just learned how to do from the marvelous @jmooring today in this thread:
Org-mode source code display control
imho, it is a good idea to learn at least some html and some css, unless all you are doing is creating a very simple website like say this sort of thing (as the theme describes):
Introduction
(it’s for a simple personal ad/blog/resume whatever stuff though it can be expanded into a much larger website as any of these minimal themes can.)
anything more, you will no doubt benefit from html and css education (as i certainly did)!