From what I have tried, it appears that you cannot set the width and height of many of the Telerik controls using CSS which makes it very difficult to create responsive sites.

 Is there a way to actually do this or is this a pipe dream?

Hi Matt,

The Telerik controls are usually rendered though complex element structure and this is why it is hard to set there size only through CSS styles. This is why we strongly advise to use each control's API when targeting a responsive layout (e.g. by setting the control's Width and Height property to 100%, making sure that all of its parents also have configured size).

You may also find useful information in the following article in order to know which controls actually support setting with and height in percent: Responsive, Adaptive and Elastic Capabilities

Regards,
Vessy
Telerik