Why do some pushbuttons in ATR aircraft have amber borders?

ATR aircraft have several peculiarities. Here is one of them. You might like those videos: Air Vanuatu flight 241:    • Wrong decisions - Air Vanuatu flight 241   Air condition:    • ATR systems - Air conditioning   Pressurization:    • ATR systems - Ventilation and pressurization   ATR systems (playlist):    • ATR systems