> some examples of what could go wrong would be really handy here. One small example that I've seen go wrong, elements don't center with CSS if you skip the do

> some examples of what could go wrong would be really handy here. One small example that I've seen go wrong, elements don't center with CSS if you skip the doctype. Seems to ignore margin-left and margin-right. Omitting the doctype basically sends the browser into "quirks mode" and then the page is rendered with old browser rendering bugs. http://en.wikipedia.org/wiki/Quirks_mode http://en.wikipedia.org/wiki/Quirks_mode