Yeah, I've done responsive grids before. Problem is, I'm currently working on a single-page web music player and it's so easy to just nail all the UI elements down. Like I might want to have the play button always appear to the left of the playback bar. But that obviously can't reflow naturally on smaller screens. Although reflowing that example won't look good either.

I guess, I'm still figuring out, if I ever actually want things to reflow. I might just need to define static rules, so that on a small screen, the play button should appear in a different grid cell, next to the previous/next buttons, for example...