Okay so i need some help Here i've added a toggle

Question

Okay so i need some help Here i've added a toggle

for dark mode / light mode (upper left)
now there are 2 problems i'm facing.
1. how am i supposed to set it to work for all the webpages linked to the homepage ?
2. when I set the light mode background to white and the text colour to black it changes the text colour on my menu bar too. how can i exclude the menu bar text colour from changing ?