#6460 No color change background last/first arrow button

[Ronja-liqd]

URL: (https://meinberlin-dev.liqd.net/dashboard/modules/umfrage-6/poll/)
user: Initiator
expected behaviour: While creatig a poll project, When there is only one question or when I have reached the first or last question, the non clickable moving up/down arrow buttons have a grey background
behaviour: The background of both buttons stays white all the time, while the non clickable arrow itself is lighter than the other
important screensize:
device & browser:
Comment/Question: Same thing happens with the creating text commenting module

Screenshot?
dev:

stage: