Well done! It summarizes a lot of theory it took me months to puzzle out on my own. One nit: At the top of each section there is a section title, at the bottom

Well done! It summarizes a lot of theory it took me months to puzzle out on my own. One nit: At the top of each section there is a section title, at the bottom of each section, there is a "Next section" title, a description, and a next section button, and on the side there is a list of sections. Some of the titles are inconsistent from list to top of current and from bottom of current to top of next. It's a little confusing right now, and there are only a few sections; when there are more, it will be far more confusing. I don't have a suggestion as to how fix it, just pointing out the confusing inconsistency.