Hi Dasha!
You can achieve this very easily using the show() / hide() methods.
All you need to do is to make two sets of the same components (that you want to change) and lay them on-top of each other.
The first set would be the original state of the component (light font, original color, etc.) while the second set will contain all the changes you’re wishing to have.
Now, use the events onMouseIn / onMouseOut for hover effect (show on mouse in - hide on mouse out) and use the onClick event to make it stay.
As for the second question, Yes!
You can achieve it using the same logic from before, while using the event “onViewportLeave”.
Its purpose is to prompt a reaction once a scrolling event (past a certain point) occurs.
Hope it helps!
Doron. 