Screenfly alternative for testing Drupal 8 sites For Responsive screen testing I am using Screenfly (http://quirktools.com/screenfly/).

Drupal 8 can not be displayed inside an iframe (see link, par. 9). This is the reason why Screenfly can not be used to test Drupal 8 sites by default.

Are there any alternatives to Screenfly for responsive screen testing?
With Google Chrome CTRL + SHIFT + I also known as right click >> Inspect

Once the Developer Tools is open, then CTRL + SHIFT + M or click the 2nd icon 





With Responsive, you can resize to whatever you want by dragging the right border