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• The PR title follows our guidelines: https://github.com/NativeScript/NativeScript/blob/master/tools/notes/CONTRIBUTING.md#commit-messages.
• There is an issue for the bug/feature this PR is for. To avoid wasting your time, it's best to open a suggestion issue first and wait for approval before working on it.
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What is the current behavior?

When triggering alert() or dialogs.confirm (from @nativescript/core/ui/dialogs), the button color is expected to follow the style of "Button" type selector defined on the css.

It works fine, however, when .ns-light or .ns-dark identifier is added in front of "Button" or "Label", it is not recognizable and does not take effect.

Please see the app.scss file below:

.ns-light Label {
  color:green;
} 

.ns-dark Label {
  color:orange;
}

.ns-light Button {
  color:yellow;
} 

.ns-dark Button {
  color:brown;
} 

There're open issues for this same bug:

1. .ns-dark doesn't apply through to dialogs #8484
2. Wrong Dialog colors on android in dark mode and no way to handle dark/light mode #9462
3. At least on iOS, some CSS styles are not applied without .ns-dark / .ns-light ; e.g. bg-danger is not applied to Buttons in dark mode. #8594

What is the new behavior?

The css style is being applied properly.