What I've been trying to figure out for years is when/why content-box would be a desirable state of affairs. Most of the time, you know the border-box width (a

What I've been trying to figure out for years is when/why content-box would be a desirable state of affairs. Most of the time, you know the border-box width (and probably the padding and border) want the browser to figure out the content-width, which is why the standard box model always seemed like a pain, because it makes you do that instead (assuming you're using units where that's even possible). I'm trying to think of a situation where that'd be useful -- where it'd be helpful from a layout perspective to start with content-width -- so I could figure out what the w3 folks were thinking, but I've always had trouble with that. Has anybody figured this out?