* Use escape-svg() function * Update theming.md
Media queries do not support CSS custom properties (CSS variables), so we've had some useless variables lying around since shipping v4. This finally removes them and the associated documentation content that explained the situation. Fixes #29012.
This allows for the build to fail if a reference isn't found.
No more Ruby dependency and most important more than 10 times less build time (at least on Windows)!
