Function
Rows are native <details> elements, so they open from the keyboard and
report their state to assistive technology without client script. A row
shows Lesson N, the lesson's first video's artwork, its title, its video
count and runtime, and the prize it redeems as a silhouette; open, it lists
each video as Video N, title and duration. Ordinals sit outside the titles
so truncation never hides them (capability course-vocabulary).
The course page's syllabus: every lesson in
sequenceorder as a disclosure row that opens to its videos.