bug(COMPONENT): Font Awesome Icons have styling problems when a mat-button is on the page

[some1awesome]

Is this a regression?

• Yes, this behavior used to work in the previous version

The previous version in which this bug was not present was

19.2.8

Description

Material buttons cause styling for mat-icon-buttons containing font awesome icons in safari and chrome

Reproduction

StackBlitz link: https://stackblitz.com/edit/stackblitz-starters-ga6nsxqe?file=src%2Fmain.ts,angular.json,src%2Fglobal_styles.css
Steps to reproduce:

1. Clicking any of the red icon buttons will toggle a variable that controls whether the mat-button is in the DOM. To view the problem make sure the button is toggled visible.

Expected Behavior

Icons will remain the same size and stay visible weather there is a material button in the DOM or not

Actual Behavior

In Chrome: Some of the taller font awesome icons will be extra tall when a button is in the DOM and be the correct size when there are no buttons in the DOM. Forcing sizes with css classes or direct styles does not impact the height of the icon when the material button is in the DOM. Note that fa-building and fa-play are two examples of taller font awesome icons while fa-toolbox is normal size. In Chrome fa-toolbox behaves how it should when the material button is in the DOM.

Here is what it looks like when the button is toggled into the DOM in chrome:

Here is what it looks like when the button is toggled out of the DOM in chrome:

In Safari: All of the font awesome icons disappear entirely when the button is in the DOM

Here is what it looks like when the button is toggled into the DOM in safari:

Here is what it looks like when the button is toggled out of the DOM in safari

Note the fourth icon is visible in safari, this is a normal home icon from material icons and I included it for reference. The other three (fa-building, fa-play, and fa-toolbox) are all font awesome icons

Environment

Angular CLI: 20.3.10
Node: 20.19.1
Package Manager: npm 10.8.2
OS: linux x64

Angular: 20.3.11
... animations, common, compiler, compiler-cli, core, forms
... platform-browser, router

Package Version

@angular-devkit/architect 0.2003.10
@angular-devkit/build-angular 20.3.10
@angular-devkit/core 20.3.10
@angular-devkit/schematics 20.3.10
@angular/cdk 20.2.13
@angular/cli 20.3.10
@angular/material 20.2.13
@schematics/angular 20.3.10
rxjs 7.8.2
typescript 5.8.3

Browsers: Chrome and Safari

[some1awesome]

So I found the css code that is causing the issue. Inside the button code there is this css:

.mat-mdc-button-base .mat-icon{min-height:fit-content;flex-shrink:0}

min-height:fit-content seems to be important for most of the button types to make the icon fill the space available to it, but it causes problem on the icon centric buttons such as the mat-icon-button or the mat-fab buttons which is why it appears that that offending css code is not included in those button implementations. I think the code needs to be:

.mat-mdc-button-base:not(.mat-mdc-icon-button):not(.mat-mdc-fab-base) .mat-icon{min-height:fit-content;flex-shrink:0}

I'm working on a pull request, but I've never done that before.