Allow using SCSS files for contentsCss stylesheets

[Lukas Neumann]

Feature Request

In the current setup, the ScssParser is able to automatically catch and compile SCSS to CSS if configured for page stylesheets. However, this does not seem to work for the RTE stylesheet, thus an additional build step is needed there. Ideally, we could define SCSS anywhere and parse to CSS as we do for pages.

This would allow to keep frontend and rte stylesheets in sync more easily, does not force the developer to add a custom build step after changing styles and reduce confusion around this issue (people manually changing css in the compiled version...).

Is your feature request related to a problem? Please describe

Configuring an SCSS file for contentsCss in the RTE config does trigger the ScssParser but @imports are not being resolved and it throws file not found errors. Seems to me this almost should work?!

Describe the solution you'd like

Allow setting

// Default.yaml
config.editor.contentsCss = 'EXT:bootstrap_package/Resources/Public/Scss/bootstrap5/rte.scss'

-> ScssParser compiles the resource to CSS automatically

Describe alternatives you've considered

Adding a manual / automatic build step to create rte.css after some trigger.