Learn Responsive Design

This course takes you on a journey through the many facets of modern responsive web design. The first few modules will ease you in with a history of where responsive design came from and a look at the fundamentals of responsive layouts. From there, you’ll learn about responsive images, typography, accessibility and more.
web.dev/learn/design/

JavaScript Error Logging – TrackJS

JavaScript Error Logging Easily Find and Reproduce JavaScript Errors TrackJS makes finding and fixing client-side errors simple. We automatically detect bugs on your website and give you a clear view of how the user got to the error.
Don’t wait for your users to report bugs. Know as soon as they happen with TrackJS.
trackjs.com/