Answer:
I am the yellow hem of the sea's blue skirt.
What can hold a car but canβt lift a feather?
I occur twice in eternity. And I'm always within sight.
Break it and it gets better, immediately set and harder to break again.
What always comes into the house through the keyhole?
What do you purposefully put lots of in and on your body, but run away from when you encounter it outside?