Change block section background


Hi! I use dark themes in my browser, (a lot at night). The white light irritates my eyes (i use algo glasses with blue light filter), but still happens.

I tried with a lot of things, i am very happy with a dark theme i have for firefox; it changes into dark all the webs i surf, including appybuilders but it didnt work with the block screen section.

So i was wondering if its possible to change the backgorund color. Since i am using appybuilder offline, maybe changin some lines of code in any place?