Add code listing CSS hack article

hack/rst2html

@@ -1,5 +1,5 @@
 #!/usr/bin/env python3
-# https://gist.github.com/mastbaum/2655700
+# Based on https://gist.github.com/mastbaum/2655700 for the basic plugin scaffolding
 
 import sys
 import re
@@ -17,6 +17,9 @@ class UnfuckedHTMLTranslator(HTMLTranslator):
         self.in_literal_block = False
 
     def visit_literal_block(self, node):
+        # Insert an empty "lineno" span before each line. We insert the line numbers using pure CSS in a ::before
+        # pseudo-element. This has the added advantage that the line numbers don't get included in text selection.
+        # These line number spans are also used to show line continuation markers when a line is wrapped.
         self.in_literal_block = True
         self.body.append(self.starttag(node, 'pre', CLASS='literal-block'))
         self.body.append('<span class="lineno"></span><span class="line">')