how to set the code highlight to dark mode?

[Zhe Lee]

I use the dark theme in my tiddlywiki but code snippet is white background, I want dark background how to set it. 
I checked the settings about appearance and haven't find the useful options.

And I check this link 

https://github.com/Manuzor/monochrome-darkvs

It said need Edit the PageTemplate. 

I search the page in the advanced search and get the error like this, so how to change the background of code block?