How changed parent border when child-widget focused use css selector?

[Yurii-huang]

Some components are drawn through the current component, and when it has a focus, the topmost border (i.e. the border of the current component) can change color based on whether there is a focus.
eg: RadioButton

And in component overlay construction, when selecting sub components, I change the top-level front node border. What should I do? Can CSS selectors do it?

class IStatic(Static)
    DEFAULT_CSS="""
    # How change IStatic broder when focused Input？
    """
    def compose(self):
           yield Input("one")
           yield Input("two")

[TomJGooding]

If I've understood your question correctly, you can use the :focus-within pseudo selector which matches widgets with a focused child widget. https://textual.textualize.io/guide/CSS/#pseudo-classes

from textual.app import App, ComposeResult
from textual.widget import Widget
from textual.widgets import Input


class FocusWithinWidget(Widget):
    DEFAULT_CSS = """
    FocusWithinWidget {
        height: auto;
        border: tall red;
        margin: 1;
    }

    FocusWithinWidget:focus-within {
        border: tall green;
    }
    """

    def compose(self) -> ComposeResult:
        yield Input()
        yield Input()


class ExampleApp(App):
    def compose(self) -> ComposeResult:
        yield FocusWithinWidget()
        yield FocusWithinWidget()
        yield FocusWithinWidget()


if __name__ == "__main__":
    app = ExampleApp()
    app.run()

[Yurii-huang]

That's right, that's what I need