diff --git a/src/epub_converter/html_epub_processor.py b/src/epub_converter/html_epub_processor.py
index 40640c1..fd29817 100644
--- a/src/epub_converter/html_epub_processor.py
+++ b/src/epub_converter/html_epub_processor.py
@@ -99,11 +99,13 @@ class HtmlEpubProcessor:
             return text
 
         title_of_chapter: str = title_of_chapter.lower()
-        title_in_text: List[Tag] = chapter_tag.find_all(lambda tag: title_of_chapter == text_preparing(tag) or \
-                                                (title_of_chapter in text_preparing(tag) and
-                                                 re.findall(r"^h[1-3]$", tag.name or chapter_tag.name)))
+        title_in_text: List[Tag] = chapter_tag.find_all(lambda tag: (title_of_chapter in text_preparing(tag) and
+                                                                     len(text_preparing(tag)) != 0 and
+                                                                     re.findall(r"^h[1-5]$", tag.name or chapter_tag.name)))
 
-        text_in_title: List[Tag] = chapter_tag.find_all(lambda tag: (text_preparing(tag) in title_of_chapter))
+        text_in_title: List[Tag] = chapter_tag.find_all(lambda tag: (text_preparing(tag) in title_of_chapter) and
+                                                        len(text_preparing(tag)) != 0 and
+                                                        re.findall(r"^h[1-5]$", tag.name or chapter_tag.name))
         if title_in_text:
             self.html_preprocessor._add_span_to_save_ids_for_links(
                 title_in_text[-1], chapter_tag)
diff --git a/src/html_presets_processor.py b/src/html_presets_processor.py
index eeba3ca..cfffe7b 100644
--- a/src/html_presets_processor.py
+++ b/src/html_presets_processor.py
@@ -27,8 +27,14 @@ class HtmlPresetsProcessor:
             kwargs["rule"]["tag_to_wrap"]))
 
     @staticmethod
-    def _decompose_tag(**kwargs):
-        kwargs["tag"].parent.attrs.update(kwargs["tag"].attrs)
+    def set_attrs_to_parent(tag, parent_tag):
+        for key in tag.attrs:
+            if key not in parent_tag.attrs:
+                parent_tag.attrs[key] = tag.attrs[key]
+
+    def _decompose_tag(self, **kwargs):
+        if kwargs["tag"].parent:
+            self.set_attrs_to_parent(kwargs["tag"], kwargs["tag"].parent)
         kwargs["tag"].decompose()
 
     @staticmethod
@@ -111,9 +117,9 @@ class HtmlPresetsProcessor:
         elif attr:
             del kwargs["tag"][attr]
 
-    @staticmethod
-    def _unwrap_tag(**kwargs):
-        kwargs["tag"].parent.attrs.update(kwargs["tag"].attrs)
+    def _unwrap_tag(self, **kwargs):
+        if kwargs["tag"].parent:
+            self.set_attrs_to_parent(kwargs["tag"], kwargs["tag"].parent)
         kwargs["tag"].unwrap()
 
     @staticmethod