Nesting CSS does not work with textual-dev

[mohammad-sayed-ahmad]

Hello everyone,
I have been recently using the textual-dev cli and I have been facing an extremely peculiar issue.
Whenever I try nesting CSS using the & it fails horibbly.

Minimum Reproducible Example:

issue.py

from textual.app import App
from textual.widgets import Static

class BasicWidget(Static):
    def compose(self):
        yield Static("Inside", classes="inside")


class BasicApp(App):
    CSS_PATH = "issue.tcss"
    def compose(self):
        yield BasicWidget()
    

if __name__ == '__main__':
    app = BasicApp()
    app.run()

issue.tcss

BasicWidget {
    background: red;
    width: 40;

    & .inside {
        background: green;
        width: 10;
    }
}

———————————————————————————————————————————————————————————
Commands Tested:
python issue.py -> Works normally
textual run issue.py --dev -> The following error in stylesheet:

 • Expected one of 'comment line', 'comment start', 'declaration name', 'declaration set end', or 'whitespace'.
 • Did you forget a semicolon at the end of a line?

[davep]

What does textual --version output?

[mohammad-sayed-ahmad]

It outputs: textual, version 0.41.0.
I am trying to update it but I don't know how.

[davep]

Not knowing your system or your environment or how you install your Python tools, it's hard to say; but this will be the cause of your problem: you have textual itself installed one way, and textual-dev installed another way, and it's older. Perhaps you have one installed into a virtual environment and the other installed globally?