[CamperBob2]

Resistor for an LED: 100 ohm

Yeah, that's why I can read a book by the blue LEDs on my alarm clock...

[_carbyau_]

https://www.3m.com/3M/en_US/p/d/b40068069/

Depending on the colour bleed though. It may wipe out all visibility of the clock numbers.

[Liftyee]

And to think a little dimming circuit with LDR/phototransistor (RoHS..) is practically electronics 101...