https://www.polymer-project.org/0.5/
Version 0.5 with core-scaffold (generic web site template), core-toolbar.

https://www.polymer-project.org/1.0/ 
With material design elements.

"Look at https://github.com/PolymerElements/app-layout-templates for a few simple scaffolds.

You should be able to copy one of those templates to replace core-scaffold in your application.

If you want a more comprehensive starting point for an app, you can also look at https://github.com/PolymerElements/polymer-starter-kit"

Example in use: http://google.github.io/dagger/ 
Code behind it: https://github.com/google/dagger/tree/gh-pages 

Also interesting: Material Design Lite. https://getmdl.io/