[jbeninger]

For my last few projects I've resorted to

*,*:before,*:after { min-width: 0}

I haven't had a single problem with it. I honestly feel this part of the spec was a mistake, given all the confusion I see. Online discussions suggest 'auto' is a counterintuitive default.

[nicoburns]

I totally agree. And not only is it unintuitive, it's bad for layout performance!