Use responsive design mode when testing a website for mobile

When developing a web app, use the responsive design mode in your browser to test your app for mobile, as a complement to testing the web app in your phone. You find the responsive design mode as a icon in the console. This way you can see if you get any mobile-specific errors in the console, and not only if it seems to work in your phone.

This made my life a bit easier and the most of you probably already know this tip, but I wish someone told me earlier.