I’ve started to contribute a Material Design App Template for Panel based on the mwc web components.
Its important (I belive) that these are web components as all the html, css and javascript is isolated in the component and does not interfere with the Bokeh html, css and javascript. Thus enabling very modern, fast and responsive templates.
If you are interested and have comments, suggestions or would like to contribute head over to the PR here
Regarding Templates there is nothing here and now.
But
@Philipp_Rudiger and I have been discussing if we could have dynamic templates and templates inside templates in order to make a more dynamic application.
I know you can just do app-app1 and page-page1 but it is an issue that is really difficult to explain to people. It also is a problem if you want to create apps that have url paths inline with for example an associated rest api. Or let the user navigate by and share urls.
The below image shows an app in a Jupyter Notebook. Theme is material/ Panel green.