Added more assertions to test.

Author: maxwasserman

pandas/tests/io/formats/test_to_html.py

@@ -1869,11 +1869,17 @@ def test_to_html_notebook_has_style(self):
         df = pd.DataFrame({"A": [1, 2, 3]})
         result = df.to_html(notebook=True)
         assert "tbody tr th:only-of-type" in result
+        assert "vertical-align: middle;" in result
+        assert "thead th" in result
+        assert "text-align: right;" in result
 
     def test_to_html_notebook_has_no_style(self):
         df = pd.DataFrame({"A": [1, 2, 3]})
         result = df.to_html()
         assert "tbody tr th:only-of-type" not in result
+        assert "vertical-align: middle;" not in result
+        assert "thead th" not in result
+        assert "text-align: right;" not in result
 
     def test_to_html_with_index_names_false(self):
         # gh-16493