Are you asking me if I use percentage values to do fluidly responsive designs? There's definitely some of that but most of the time it's even simpler than that

Are you asking me if I use percentage values to do fluidly responsive designs? There's definitely some of that but most of the time it's even simpler than that - just defining a max width or height on something and letting things expand to fill their containers. Then you only have a few big containers in the entire layout to worry about :)