Feature 424 block design & features
The block is a scroll-driven variation of feature423. Instead of pinning the whole section, the chapters scroll past at their natural pace while a product screenshot stays fixed on the left.
Each chapter has a title, a short paragraph and two points, marked by a left rule. When a chapter crosses the middle of the viewport it becomes active: its rule darkens, the others fade back, and the screenshot crossfades to match. A row of small indicators under the screenshot shows which chapter is active.
The active chapter is tracked with an IntersectionObserver, so nothing runs on every scroll frame.
Below the large breakpoint the sticky screenshot is hidden and each chapter shows its own screenshot under its text.