Have your tried the same CSS for the button?

You can use same CSS for the button also that you used for icon.

If you did not try for button then please use it first and let us know if its working or not.

<mat-icon style="color: red; position: fixed; bottom: 0; right: 0;" (click)="showMenu()">add_circle</mat-icon>

And if you got the answer of previous question, then kindly mark the reply or replies as answer.

Add Button on Bottom right Corner in Angular