There's also a couple of other helpers like `max-width-*` which ensure responsiveness as the screen grows larger. Things like adding the `Classes.FILL` (which causes a button/control to go full width of its container) are useful for making things seem more like mobile (where buttons often are full width of the device, minus padding)
All in all, while it's a slight bummer than Blueprint isn't just responsive out of the box, I haven't really found that to be a deterrent to getting things done.