I completed this theme/site early 2018 and it happens to be my first WordPress theme. It uses Bootstrap (mostly for layout/grid/responsiveness) and was built just using this tutorial I found and my own imagination.
It should be noted that this was waaaay before I took a class (CAS211w) to learn how to properly build a WordPress theme. It does utilize the WordPress API, but is really just the bare minimum and leaves a lot to be desired in my opinion. The focus was to allow the site owners to easily update the site by storing site content in WP posts (type: posts).
A year later or so, I got real/actual training on theme-building in WP and created this: https://github.com/furyuri/nightlife-wp-theme
At any rate, it is still serving it's purpose and is alive and well on http://www.essentialmassageandwellness.com/
- Uri