How to make CSS changes to Core?

We've been grappling with this problem for years, lacking any consensus on the best way forward. With discussions of Backdrop CMS 2.x underway, now seems like a good time to figure this out and make a decision. 

In this discussion, I'd like to review the options available and see where the current consensus is at. Much time has passed since this was discussed in detail and some folks may have changed their opinions. Can we build towards a consensus solution?

This is one of those issues that might require a real-time discussion to break the log jam.

Using ProboCI For Backdrop Developer and User Testing

ProboCI is an open source platform for the testing, debugging, and collaborating on web based projects for Backdrop CMS, Drupal, Wordpress and any PHP based project. It operates on pull requests and generates specific build environments that can be scripted and standardized to provide a uniform way to do both automated and manual testing of modules and interfaces.

Customize Your Site with Existing Themes and Modules

In this mornings session there were questions about how to customize the appearance of your site without creating a new theme.

Let's talk about things like:

  • When do you need a custom theme and when can you avoid it?
  • When to create a sub-theme of an existing theme.
  • Ways to modify an existing theme without a subtheme.
    • CSS Injector 
    • CSS Editor
  • Modules that do things that might also be done in a theme
    • Fancy Blocks
    • Configurable Block Styles
    • Sticky Menus