Handle English language for blockquotes

site.py

@@ -54,7 +54,24 @@ class MarkRenderer(mistune.HTMLRenderer):
         return "<mark>" + text + "</mark>"
 
 
-class ImgsWithSizesRenderer(MarkRenderer):
+class BlockquoteLanguageRenderer(MarkRenderer):
+    """Sets the English language attribute for blockquotes with `[en]` prefix."""
+
+    def _get_language(self, text):
+        if text.startswith("<p>[en] "):
+            return "en", text.replace("<p>[en] ", "<p>")
+        else:
+            return None, text
+
+    def block_quote(self, text):
+        language, text = self._get_language(text)
+        if language:
+            return f'\n<blockquote lang="{language}">\n{text}</blockquote>\n'
+        else:
+            return f"<blockquote>\n{text}</blockquote>\n"
+
+
+class ImgsWithSizesRenderer(BlockquoteLanguageRenderer):
     """Renders images as <figure>s and add sizes (useful for lazy loading)."""
 
     def paragraph(self, text):