change theme background colour not working

Following this example from https://stackoverflow.com/questions/65033675/how-to-switch-from-light-to-dark-theme-in-ipyvuetify
it doesn't change the coloou.
Is there any other way to do it?

Thanks

A trick is to add an opaque Overlay component as background (z-index=-1) and change its color upon switching the ipyvuetify theme:

import ipyvuetify as v

dark_bg = '#7FFF00'
light_bg = '#7FFF00'

bg = v.Overlay(
    color=dark_bg if v.theme.dark==True else light_bg, 
    opacity=1, 
    style_='transition:unset', 
    z_index=-1
)

def bg_switch(widget, event, data):
    v.theme.dark = not v.theme.dark
    bg.color = dark_bg if v.theme.dark==True else light_bg

btn = v.Btn(children=[v.Icon(children=['mdi-theme-light-dark'])])
btn.on_event('click', bg_switch)

v.Container(children=[bg, btn])

Start by reproducing the linked Stack Overflow example in a Jupyter notebook, using the issue's v.theme, Overlay, and background-switch handler entry points. Inspect how ipyvuetify applies theme and Overlay colors, then verify that switching the theme visibly changes the page background without requiring an unsupported workaround.