Ionic V4 - How do you change button background color without --background?

#1

How do you change button background color without --background?
Is there --background-color ?
Too many such kind of problems in IONIC4 web component .

For just to change background color, NOT WHOLE BACKGROUND, to using BACKGROUND is very very STUPID , because I don’t want to override background the other attributes.

ion-button {
    --background: orangered;
}

Is using web component with shadow DOM just for FANCY? It seems not practical, and increase development time, who decided to change to web component with shadow dom?
Ionic