Based on the intellij-rust plugin site.

Install Ruby and Bundler. There is .ruby-version file for rbenv if you like. You will probably need GCC, Make, AutoConf and NodeJS installed.

$ bundle install
$ bundle exec jekyll serve

If you are using Windows, it's better not to fight with Ruby Installer. I use WSL and works pretty flawlessly, except file change watching (see tracking issue). So you'll have to run this instead:

$ bundle exec jekyll serve --no-watch

To workaround lack of watching, you can do:

$ bundle exec jekyll serve --detach
$ while (bundle exec jekyll build --incremental); do sleep 5; done