Tried to see where to leak is coming from , but didn't catch it. However seems to be getting smaller ?Could be a slight weep from the water pump. Try putting a phone camera in the gap through the tray.
my mechanic thinks it's this part (replaced last week) as coolant was spiling out of it.As long as your coolant is between max and min that's fine, overfilling can lead to it being forced out of the expansion tank.
Mine generally is happy about a few mm below the min line when cold, when warm it's almost exactly at the max line.
When you next park the car, try and mark a point you can relate back to, maybe position of front wheels with a bit of tape, and start with a clean floor, that way you can tell roughly where the leak is coming from, it won't be exact as coolant can track along numerous parts, but should give you an idea of where to concentrate.