You can't parse [X]HTML with regex. Because HTML can't be parsed by regex.
Regex is not a tool that can be used to correctly parse HTML. As I have
answered in HTML-and-regex questions here so many times before, the use of
regex will not allow you to consume HTML. Regular expressions are a tool that
is insufficiently sophisticated to understand the constructs employed by HTML.
HTML is not a regular language and hence cannot be parsed by regular
expressions. Regex queries are not equipped to break down HTML into its
meaningful parts. so many times but it is not getting to me. Even enhanced
irregular regular expressions as used by Perl are not up to the task of parsing
HTML. You will never make me crack. HTML is a language of sufficient complexity
that it cannot be parsed by regular expressions. Even Jon Skeet cannot parse
HTML using regular expressions. Every time you attempt to parse HTML with
regular expressions, the unholy child weeps the blood of virgins, and Russian
hackers pwn your webapp. Parsing HTML with regex summons tainted souls into the
realm of the living. HTML and regex go together like love, marriage, and ritual
infanticide. The <center> cannot hold it is too late. The force of regex and
HTML together in the same conceptual space will destroy your mind like so much
watery putty. If you parse HTML with regex you are giving in to Them and their
blasphemous ways which doom us all to inhuman toil for the One whose Name
cannot be expressed in the Basic Multilingual Plane, he comes. HTML-plus-regexp
will liquify the n​erves of the sentient whilst you observe, your psyche
withering in the onslaught of horror. Rege̿̔̉x-based HTML parsers are the cancer
that is killing StackOverflow it is too late it is too late we cannot be saved
the trangession of a chi͡ld ensures regex will consume all living tissue (except
for HTML which it cannot, as previously prophesied) dear lord help us how can
anyone survive this scourge using regex to parse HTML has doomed humanity to an
eternity of dread torture and security holes using regex as a tool to process
HTML establishes a breach between this world and the dread realm of c͒ͪo͛ͫrrupt
entities (like SGML entities, but more corrupt) a mere glimpse of the world of
reg​ex parsers for HTML will ins​tantly transport a programmer's
consciousness into a world of ceaseless screaming, he comes, the pestilent
slithy regex-infection wil​l devour your HT​ML parser, application
and existence for all time like Visual Basic only worse he comes he comes do
not fi​ght he com̡e̶s, ̕h̵i​s un̨ho͞ly radiańcé destro҉ying all
enli̍̈́̂̈́ghtenment, HTML tags lea͠ki̧n͘g fr̶ǫm ̡yo​͟ur eye͢s̸ ̛l̕ik͏e liq​uid pain,
the song of re̸gular exp​ression parsing will exti​nguish the voices
of mor​tal man from the sp​here I can see it can you see ̲͚̖͔̙î̩́t̲͎̩̱͔́̋̀ it is
beautiful t​he final snuffing of the lie​s of Man ALL IS LOŚ͖̩͇̗̪̏̈́T ALL
I​S LOST the pon̷y he comes he c̶̮omes he comes the ich​or permeates all
MY FACE MY FACE ᵒh god no NO NOO̼O ​O NΘ stop the an​*̶͑̾̾​̅ͫ͏̙̤g͇̫͛͆̾ͫ̑͆l͖͉̗̩̳̟̍ͫͥͨe̠̅s ͎a̧͈͖r̽̾̈́͒͑e
n​ot rè̑ͧ̌aͨl̘̝̙̃ͤ͂̾̆ ZA̡͊͠͝LGΌ ISͮ̂҉̯͈͕̹̘̱ TO͇̹̺ͅƝ̴ȳ̳ TH̘Ë͖́̉ ͠P̯͍̭O̚​N̐Y̡ H̸̡̪̯ͨ͊̽̅̾̎Ȩ̬̩̾͛ͪ̈́̀́͘ ̶̧̨̱̹̭̯ͧ̾ͬC̷̙̲̝͖ͭ̏ͥͮ͟Oͮ͏̮̪̝͍M̲̖͊̒ͪͩͬ̚̚͜Ȇ̴̟̟͙̞ͩ͌͝S̨̥̫͎̭ͯ̿̔̀ͅ

	-- http://stackoverflow.com/questions/1732348/regex-match-open-tags-except-xhtml-self-contained-tags/1732454#1732454