Change color of Ionic 4 Back Button

#1

I’m looking at the documentation for the back button (https://ionicframework.com/docs/api/back-button) and trying to change the color of it using

ion-back-button {
  --color: #fff;
}

and it doesn’t have any effect. I am new to css variables so I’m not sure how to troubleshoot. What am I doing incorrectly?

#2

I did it like this:

ion-title,
ion-buttons {
color: #ffffff;
}
#3

try mentioning the color you want.
i don’t think this is right way to code.
Regards.