How to override material CSS styles?

Question

I use Angular Material 2.

There is one CSS style in material CSS:

.mat-radio-button.mat-accent .mat-radio-inner-circle {
  background-color: #fff;
}

I tried to override it in custom CSS file like:

.mat-radio-button.mat-accent .mat-radio-inner-circle {   background-color: red !important; }

Also I tried this:

/deep/ .mat-radio-button.mat-accent .mat-radio-inner-circle {
  background-color: red !important;
}

It does not work, how to do this right and in which place?