The following code displays correctly in Chrome or IE (the image is 200px wide). In Firefox and Opera the max-width style is ignored completely. Why does this
For a specific case, there's another workaround that I accidently found online: if you use display: table; + display: table-cell; to mimic a two (or more) column layout in a responsive site, try this instead: give the sidebar a widht of, say, 350px and the main content part of the site a width like width: calc(100% - 360px); . That did the trick for me, and the bonus was I needed a fixed width sidebar. I giess that will work with em's too.
Of course, this is js-dependent, but nowadays should be more than OK.