Dark image background

Please, could you explain how works the option "dark image background".

I use light background photo on the frontpage and dark photos on other pages.
Nothing happen when I turn on this option. Only on the one page the links changed color into white (http://mytric68.bget.ru/category/blog/)
And athother strange thing on the frontpage - after scrolling the logo changing to the light variant

Hi,

Dark Image Background - When is it enabled, menu and logo text is displayed as white text in order to better show up on dark backgrounds. When disabled, the text will be black to better show up on light backgrounds.
Dark Image Background on Frontpage - The same control as above, but specific only to the frontpage.

If you are not using a text logo - you have also options to upload default and "dark" image logo (Site Identity panel)

Thank you for answer. Basically I understand how it should work. But in my case it doesn't work propertly.
Just look at link in my first post.

I would like to understand where is the problem.

Could you please provide me with a URL to your website and back-end access via PM (click the “Private Message” text underneath my avatar) so that I may analyze it?