bug: controlling ion-button paddings fails below 12px

### Prerequisites

- [x] I have read the [Contributing Guidelines](https://github.com/ionic-team/ionic-framework/blob/main/docs/CONTRIBUTING.md#creating-an-issue).
- [x] I agree to follow the [Code of Conduct](https://ionicframework.com/code-of-conduct).
- [x] I have searched for [existing issues](https://github.com/ionic-team/ionic-framework/issues) that already report this problem, without success.

### Ionic Framework Version

v8.x

### Current Behavior

Setting paddings to anything below 12px does not affect the button styling.

### Expected Behavior

Setting paddings to any value should affect button styling

### Steps to Reproduce

1. Open the stackblitz url provided
2. Go to main.css (should open by default)
3. Start uncommenting/commenting parts to observe the issue

### Code Reproduction URL

https://stackblitz.com/edit/ayv7yvbl?file=src%2Fmain.css

### Ionic Info

Ionic:

Ionic CLI : 7.2.1
Ionic Framework : @ionic/react 8.5.8

Capacitor:

Capacitor CLI : 7.2.0
@capacitor/android : 7.2.0
@capacitor/core : 7.2.0
@capacitor/ios : 7.2.0

Utility:

cordova-res : not installed globally
native-run : 2.0.1

System:

NodeJS : v22.15.0
npm : 10.9.2
OS : macOS

### Additional Information

The button padding styling is mentioned in [the documentation](https://ionicframework.com/docs/api/button#css-custom-properties) and it has no constraints.