Option to install LEDs on the back side of the PCB
Depending on your application for the mood light you may want to mount the LEDs on the back side of the PCB so you don't see the other components.
If you do this you need to be careful to fit them in the correct location and orientation since there is no overlay on the back side.
The photo (right) shows where to fit them and the correct orientation. Since the holes in the PCB are plated through you will solder the leads on the top side of the board.