epub converter: fix tables

src/html_epub_preprocessor.py

@@ -68,7 +68,7 @@ def preprocess_figure():
 def preprocess_table(body_tag: BeautifulSoup):
     tables = body_tag.find_all("table")
     for table in tables:
-        tds = table.find_all("td")
+        tds = table.find_all(re.compile("td|th|tr"))
 
         border_sizes = []
         for td in tds:
@@ -101,6 +101,9 @@ def preprocess_table(body_tag: BeautifulSoup):
             if td.attrs.get('style'):
                 td.attrs['style'] = td.attrs['style'].replace('border:0;', '')
 
+            if td.attrs.get('style') == '':
+                del td.attrs['style']
+
         if border_sizes:
             border_size = sum(border_sizes) / len(border_sizes)
             table.attrs['border'] = f'{border_size:.2}'