Responsive Device Switcher
In short
With Responsive Device Switcher you can make changes to your website responsively. Simply increase or decrease the width of the window and the content of your website will be changed. You can switch between the standard view of your website and the responsive view at any time. Any changes you have made will be preserved.
Due to framing restrictions on the website, the reponsive device switcher may not be able to load the website. You can find out how to solve this problem in the "Troubleshooting“.
Step-by-step guide
How to use the Responsive Device Switcher.