Audi Tachometer: Red to Blue Conversion

Hello,

I converted the speedometer in my Audi A4 1.9l TDI from red LEDs to blue LEDs. You know, blue makes people happy...

So far, it looks quite good, but I'm having trouble with the LCD displays for the odometer reading and the outdoor thermometer.

In the original version, there is a white plastic plate behind the speedometer display, which is still coated red on top, and for the A-thermometer, there is a red, transparent film.

If I remove those parts, you can clearly see the LEDs underneath the LCD displays, and even when I replace them with blue film, you can still see them.

Does anyone have any ideas? How did VW do that?

Regards,
Jackson.