Guidelines to develop Paper UI

There are any guidelines/documents, for new users start to develop new features on paper ui?

If there are it will be in the Eclipse SmartHome site. I don’t think there are any specific guidelines but before spending a lot of effort on changes I would discuss them on the ESH forum.

Here’s the PaperUI bundle for ESH:

You’ll need to run npm i in this folder in order to install all necessary node packages.
After that simply run gulp serve.

But as @rlkoshak said - it’s worth submitting an issue before making changes.
Good luck!