Not responsive, but @media queries on width and re-scaling width, margin, background colour, and border colour is what gets you that.
Motherfucking Website. No sidenotes. but other bones of my basic design. http://codepen.io/dredmorbius/pen/KpMqqB
Daniel Bos's sidenote implementation: http://loadingdata.nl/waves/
(Degrades nicely for non-CSS viewers, not responsive.)