Fix headings cleaning problem

src/epub_converter/html_epub_preprocessor.py

@@ -186,12 +186,13 @@ def _remove_headings_content(content_tag, title_of_chapter: str):
     for tag in content_tag.contents:
         text = tag if isinstance(tag, NavigableString) else tag.text
         if text:
-            text = re.sub(r"^[\s\xa0]+|[\s\xa0]+$", " ", text).lower()
+            text = re.sub(r"[\s\xa0]", " ", text).lower()
+            text = text.strip() # delete extra spaces
             if title_of_chapter == text or \
                     (title_of_chapter in text and re.findall(r"^h[1-3]$", tag.name)):
                 _add_span_to_save_ids_for_links(tag, content_tag)
                 tag.extract()
-            break
+                break
 
 
 # todo remove