Google have released Web Fundamentals - a comprehensive resource for multi-device web development - and a Web Starter Kit boilerplate. They wrote a blog post about it all called Web Fundamentals and Web Starter Kit: Resources for Modern Web Development:
Web Fundamentals’ guidelines are intended to be fundamental to the platform: useful no matter which framework you choose or which browser your users run. We have articles about responsive layouts, forms, touch, media, performance, device capabilities, and setting up a development workflow. Articles cover both coding and design. For example, the article on layout design patterns explains both the usability tradeoffs between different layout options and how to implement them. The performance section complements PageSpeed Insights, an auditing tool that encourages instant (<1 second) mobile web sites.
Designed to help you apply Web Fundamentals’ best practices in new projects, Web Starter Kit is a lightweight boilerplate with templates and tooling. Web Starter Kit gives you responsive layout, a visual style guide, and optional workflow features like performance optimization so you can keep your pages lean and fast.