Hi all, I'm wondering if a certain tool exists for a kind of advanced note-taking of technical material (math, CS, engineering, Physics, etc). Originally, I just wanted to type all my course notes from college into word or possible rewrite them on paper l format. But I thought about it more carefully, and long story short, I concluded that what I really want to do is be able to type hierarchical notes in pdfs. I want to be able to open my digital/PDF version of my notes for a course I took before and initially see what might look like a cheat/formula sheet for a final exam, but under each equation or section, there could be a tab to expand/collapse sections for more detail, and even expandable/collapsible sections within those for maybe further details or examples .. etc, so that in a sense, you'd have a single file of notes that serves as a quick reference, but if you expanded EVERYTHING, it could be as large as 100 pages and be as comprehensive as a terse textbook / lecture notes. Does any digital tool like this exist at all? I was ideally hoping i could do this in ## \LaTeX ## if possible, but I'm open to other ideas. Thanks.