Note: I didn't create this post. The original author is here.
The User Pages default domain and host location (repository name) on GitHub is username.github.io. User Pages are automatically served over HTTPS from the master branch.
As far as I can tell, Jekyll is already enabled by default. In other words, there is no setting that you have to "turn on" in order to get Jekyll to start working on GitHub Pages. Simply by following the directory structure that Jekyll requires will result in the site getting built by Jekyll.
I initially selected the Cayman theme as I found it the most pleasing among the different themes that are "officially supported" by GitHub Pages. However, it doesn't come with any sort of navigation bar, so I found the Cayman Blog theme which does.
The problem is that Cayman and Cayman Blog do not use Bootstrap: in fact, they define CSS rules that occasionally conflict with Bootstrap. Consequently, I quit using any pre-defined theme and just used Bootstrap 4 (alpha v6) myself.
Getting syntax highlighting to work required 3 steps.
highlighter: rouge to _config.ymlrouge-github.css to the /css/ folder. I copied it over from the Cayman theme repo, which is allowed per its CC0 license.rouge-github.css stylesheet in the default.html layout.To avoid unnecessarily downloading this extra syntax-highlighting CSS on pages without code, I require that any page with code on it to set use_code: true in its front matter.
Displaying LaTeX equations using MathJax is surprisingly easy. The only necessary step is to link to the MathJax JavaScript file.
To avoid unnecessarily downloading this extra JS file on pages without math formulas, I require that any page with math formulas on it to set use_math: true in its front matter.
Vanilla Markdown is a bit limited in the formatting that it supports. Hence, GitHub (by default) adds support for extra features such as tables and emoji. The GitHub Markdown cheat sheet can be found here.