Changing CSS as You Scroll with Stimulus | Rails Designer

With the power of JavaScript in a small, reusable Stimulus controller, recreate the workings of the MutationObserverTweaking the UI element or component based on some scroll state, can help make it stand out or guide focus from the user. I recently had to add such a feature where a, potential, long list of items could scroll below the navigation’s leader element. If the list “touched” the leader, extra CSS classes would be added, making sure it would still be eligible with the items scrolled below it. Something like this:.