CSS not working for Vaadin 8 Designer views in IntelliJ (works fine in Eclipse)

[starg09]

Steps to reproduce

Open a view design for Vaadin 8 in IntelliJ, then in Eclipse

Actual behavior

The IntelliJ editor has no CSS applied to the editor's view:

IntelliJ's internal editor

Opening with an external browser (console log attached)

Expected behavior

I'd expect the view to apply the project's css, just as it does in Eclipse by opening the exact same project and views, no additional changes:

Eclipse's internal editor

Opening with an external browser

IDE, Designer and OS version

• Windows 11 Pro
• IntelliJ IDEA 2023.2.3 (Ultimate Edition)
  • Build #IU-232.10072.27, built on October 11, 2023
  • Runtime version: 17.0.8.1+7-b1000.32 amd64
  • VM: OpenJDK 64-Bit Server VM by JetBrains s.r.o.
• Vaadin Designer (IntelliJ plugin) 4.6.23
• Project is a maven project running Vaadin 8.14.3

Just as to also include for reference, the working Eclipse version is, on the same machine:

• Eclipse IDE for Enterprise Java and Web Developers (includes Incubating components)
  • Version: 2023-09 (4.29.0)
  • Build id: 20230907-1323
• Vaadin Designer (Eclipse plugin) 4.6.23
• Same maven vaadin 8 project as above

[starg09]

Update with additional info on this, as I'm slightly dumb and only recently realized:

We do have a custom "apptheme" theme. It's made in scss, which apparently is caught on by eclipse. In IntelliJ however, we get the result shown above. As a workaround, the valo theme can be selected for debugging on an usable preview, but theme must be rolled back to apptheme before actually commiting.

Feel free to ask anything that may be relevant in this regard, if useful 😊

[mcollovati]

@szolo is this ticket still valid?