personally i would just do it with css in the project - not as a gem.
bootstrap is a css framework, I’m sure you could use it as a base to do whatever you want.
As for how to do it, if you are not experienced at css I’m not sure how to help. There are lots of great youtube videos on css. Last time I looked at BS it was a bit complicated to get into a project.
Somewhere there is a gallery of jekyll themes - some are probably gem based themes but there were some that had the css/layouts in the main project - you could find one of those and start poking around.
The docs have some info on working with gem based themes.
Yes I’ve been readin a lot, what i cant find how to do is to Insert Bootstrap 4 on my theme Project, any guidance for that?
Platform Win 10
used: jekyll new-theme on git bash and created one index.md for testing my theme.
Managed to creat a main.scss and partial scss inside _scss but i dont get how to use bootstrap in here.