It sounds like you're headed towards XHTML. The rise and fall of XHTML is well documented and you can binge the whole thing if you're so inclined.
But my summarization is that the reason it doesn't work is that strict document specs are too strict for humans. And at a time when there was legitimate browser competition, the one that made a "best effort" to render invalid content was the winner.
But my summarization is that the reason it doesn't work is that strict document specs are too strict for humans. And at a time when there was legitimate browser competition, the one that made a "best effort" to render invalid content was the winner.