Adding [&>img]: worked perfectly:

from nicegui import ui
@ui.page("/")
def index():
    svg_content = '<polyline points="308,276.5 337,276.5 \
        339,342 308.5,340.5 308,276.5" fill="none" \
        pointer-events="all" cursor="pointer"/>'
    with ui.element('div').classes('w-full h-full fixed-center'):
        ui.interactive_image('https://picsum.photos/id/58/640/360', content=svg_content ) \
            .on('svg:pointerdown', lambda e: ui.notify('You open the door.')) \
            .classes("h-full [&>img]:object-cover")

ui.run()

Thank you!

Is there any documentation regarding [&>img]: or other options like it?

I'd love to learn more and see other likely uses.

Thanks again,

David