This theme is compatible with Bootstrap if you choose to use it in your pages or posts. Here is a little demo with a code snippet, look at the source to see how the HTML and markdown get tangled.
This post showcases Font Awesome icons available in Type-on-Strap. Icons are included via the bundled Font Awesome 6 stylesheet.
This post showcases KaTeX math rendering. Make sure katex: true is set in _config.yml.
Jekyll supports the use of Markdown with inline HTML tags which makes it easier to quickly write posts with Jekyll, without having to worry too much about text formatting. A sample of the formatting follows.