Currently the UserCSS's are just a big blob of CSS with each piece unrelated to the next. It would be nice if we replaced the system preference with individual "snippets". These could live somewhere like HTML customizations. This would bring more organization to CSS customization. It could also allow staff to see how created/edited/deleted certain blocks much easier. It could also make it easier to incorporate different permission checks for who can create/edit/delete CSS Similar to Bug 38706. This could also be helpful for adding CSS to Mana eventually?