Is there anyway you can make it so admins can add preset css codes for people to adjust, like the backgrounds on certain elements, etc. 

like body background, page_wrap, or page_container backgrounds? Maybe even module header backgrounds, etc. 

Each theme has a different setup so this would help admins set the themes to work the way they want them to. 

Also different themes use different means of changing background color. page_padding, body,html, body, or page_wrap, etc.