from textual.app import App, ComposeResult
from textual.widgets import Markdown, TabbedContent, TabPane

class TabbedApp(App):
    def compose(self) -> ComposeResult:
        with TabbedContent(initial="tab1"):
            with TabPane("First Tab", id="tab1"):
                yield Markdown("This is the content of the first tab.")
            with TabPane("Second Tab", id="tab2"):
                yield Markdown("This is the content of the second tab.")

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