Have an error in the html file

[cosminciuta]

Hi there,

I basically reproduced the component. But I got this error in back-to-top.component.html and I don't know how to fix it.
It says:

'mat-icon' is not a known element:

1. If 'mat-icon' is an Angular component, then verify that it is part of this module.
2. If 'mat-icon' is a Web Component then add 'CUSTOM_ELEMENTS_SCHEMA' to the '@NgModule.schemas' of this component to suppress this message.ngtsc(-998001)
   back-to-top.component.ts(10, 44): Error occurs in the template of component BackToTopComponent.

Best regards,
Cosmin