They could have used `<pre>`, they could have introduced an `<en-codeblock>` element.
But no. They choose a custom CSS style `-en-codeblock:true`.

This is obviously fragile.

Two problems:

1. distinguishing styled divs that are made by user (so may contain markdown) and the ones produced by webclips which need to be copied verbatim
2. avoid fooling markdown2 which does not tag matching to find boundaries of HTML so it gets confused with nested divs

Problem 1 is solved by looking for the `-evernote-webclip` style (not documented)
Problem 2 is solved by using verbatim output for webclip contents, and prepending a space to each line so that nested `</div>` are ignored.