Hi Paul. I think Dmitry meant not this, but control inside the Page Builder interface. In view of the controller 575> 320 (Mim-Width View). Also, existing now controllers are not objective. For example, when you configure things focusing on the Phone View, which in the Page Builder interface is 480px wide, in reality you set up the range 767> 576. Thus, for the range 575> 320, there is no control or settings. Every time we have to tune it through CSS. The same applies to control 1199> 992. Every time we need to configure it range through CSS.
For example, I want to change the font size on the screens less than 575 px. I can't do it in any way using the Page Builder interface. Only via css.

And 320 not as breackpoint, but as min width view contoller will be good feature