I decided to simplify the stylesheets because there were no submission last time which I imagine is because of how messy it all looked like and you didn't really understand which attributes were affected in the first place.

Here is how the new format looks like:
:root.theme-(stylesheetname){
/* Background, Posts, Sidebar, Navbar, etc.*/
--background-color-one: ;
--background-color-two: ;
--sidebar-favicon-color: ;
--page-background-image: url('');
--page-background-image-repeat: ;
--page-background-image-position: ;
--page-background-image-attachment: ;
--text: ;
--font-size: 10pt;
--font-family: 'Tahoma';
--link: ;
--link-hover: ;
--subject-and-timestamp-hover: ;
--name: ;
--metadata: ;
--main-border: ;
--main: ;
--informational: ;
--warning: ;
--warning-hover: ;
/* Home, Rules, News */
--informational-color: ;
--informational-border-color: ;
/* 22chan Features */
--reply-counter: ;
--search-highlighter: ;
--audio-player: ;
--audio-player-volume-slider: ;
--audio-player-volume-slider-border:
--tags: ;
--sage: ;
/* 22chan Styling */
--backquote-highlighter: ;
--quote: ;
--code: ;
--note: ;
}

--page-background-image
If you want to use a image for the background you can insert a url if not leave it empty.
--page-background-image-repeat
If you don't want the image to repeat insert "no-repeat"
--page-background-image-position
The positioning of the image for example if you want it to be shown on the left insert "top left" or if you want it to be shown on the right side of the screen insert "top right"
--page-background-image-attachment
If you want the image to be scrollable leave it empty but if you want it to stay fixed on the screen insert "fixed"

To see how your stylesheet looks like open the dev console by pressing F12 and proceeding to the "Inspector" tab on FireFox or "Element" tab on Chrome and modify the current active stylesheet to your liking and then submit here with the name of the stylesheet.