Abstract: Techniques for responsive design controls are described. A user interface is provided having a breakpoint bar configured to display multiple selectable breakpoints. When the breakpoints are selected, digital content displayed on a design surface located adjacent to the breakpoint bar is resized according to a relative size of the breakpoint. The user interface additionally has a central axis along which the multiple breakpoints are distributed. The design surface enables the digital content to be viewed and resized around the central axis responsive to selection of one of the breakpoints. Additional tools and techniques are provided to implement responsive design controls.