am: use the download download link beneath the code to capture it rather than copy-pasting... or remove the newlines from what you copy-pasted until you have the $output as a single line in your editor.

and... updating the previous: I realized, belatedly, that you appear to want to capture the contents of all the tag pairs, rather than just the first. Sorry, the code I posted captures only the first and so far, I haven't worked out a simple (aka, "elegant") and understandable way to do them all with a regex. CF advise to use an html parser or (new suggestion) a module designed to deal with matching pairs. Perhaps wiser monks will offer more particular suggestions.