But surely that is in itself counter to how css is supposed to work at a very fundamental level? If you want to render different content for different browsers

But surely that is in itself counter to how css is supposed to work at a very fundamental level? If you want to render different content for different browsers, I'm not convinced that is a function of stylesheets, not should it be. If my layout needs extra padding or whatever if a div is a flexbox, rather than display:table, I would consider that to be an implementation issue rather than something I would want to cover with additional code. I might just be completely missing the point, but it feels like a bandaid.