Calculus Book — written by Throstur05. 798 words across 2 lectures, running from limits and continuity to wherever the book is taken. Nothing is condensed: every paragraph, sub-heading, table, Spanish example with its English and practice question is stored in reading order and shown in reading order, so what appears on screen is the lecture as it was written rather than a summary of it.
This one is written by hand rather than gathered: the source is a plain text file in KaTeX, rebuilt into JSON by a script whenever a lecture is added, so the shelf and the reader follow the book as it grows. Twenty-one ways through the same text.
Six read it — one lecture entire, an index of every lecture number down the left, a reader that hands you a single section at a time, a continuous scroll, an outline of the section headings, and a syllabus of the whole course. Eight take it apart — every Spanish line beside its English, the glossary lifted out of the tables, the tables on their own, flashcards Spanish side first, the practice questions, a drill that pulls a random example in either direction, and the objectives and closing summaries.
Seven keep track — homework, cultural notes, an accent-insensitive search across every block, starred lines, a page of your own notes per lecture, a progress board, and a printable handout. Forty-six colour palettes on a white default with dark one click away, eight colour roles editable by hand, twelve page layouts from a narrow reading column through ruled notebook paper and two magazine columns to a monospaced terminal, seven typefaces with a separate face for the Spanish, and sliders for text size, leading and line length.
The English can be hidden to read the Spanish cold, or the Spanish hidden to work back the other way. Progress, stars and notes autosave, with JSON export and import.