I am sometimes lazy and install Franklin globally, but I would recommend setting up an environment for that.
I checked your code and why the CSS is not found. Your rendered HTML has a code line
/assets/css/style.css?v=9999407b91cb53fb3aee8b1f3afede4e6257aab8
so that is an existing file and seems to work, so could you check the same for the other CSS you load? I would assume that the subdomain might be the problem, because on localhost you do not have that.
The next thing that I find surprising is the @def title on the GitHub page – are you sure Frankling runs correctly on CI? Ah it seems Franklin runs according to Update · aenarete/aenarete.github.io@9999407 · GitHub – so then I am surprised.
So final thing I see, maybe the last line here aenarete.github.io/.github/workflows/Deploy.yml at main · aenarete/aenarete.github.io · GitHub might need adaption? Do you locally get a __site folder when rendering Franklin? (it seems the CI script is a bit newer than the one I use).
or in short: We mainly have to find out which fancy CSS you get locally but not in CI 
edit: For the first point with the path, see also Template not applied to site generated by Franklin.jl - #5 by kellertuer