Best-Practice on how to change MD Styles

Ionic Framework ionic-v3
1

I have these default styles in Droid:

image

To get rid of them I did in app.core.css

.item-input.ng-valid.input-has-value::after,
.item-input.ng-invalid.ng-touched::after,
.item-input.input-has-focus::after,
.item-input.ng-valid.input-has-value::after,
.item-input.ng-valid.input-has-value.input-has-focus::after ,
.item-input.ng-invalid.ng-touched::after,
.item-input.ng-invalid.ng-touched.input-has-focus::after, {
    border:none;
}

This works.
Now is there a better way to do this?