From 00c9550ad089bb4997ee03f0b98ddc77128a1b65 Mon Sep 17 00:00:00 2001
From: JoseNavy <72418396+JoseNavy@users.noreply.github.com>
Date: Tue, 22 Dec 2020 13:33:36 -0700
Subject: [PATCH] Backport PR #38533: BUG&TST: HTML formatting error in
 Styler.render() in rowspan attribute

---
 doc/source/whatsnew/v1.2.0.rst        |  4 ++++
 pandas/io/formats/style.py            |  2 +-
 pandas/tests/io/formats/test_style.py | 11 ++++++++++-
 3 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/doc/source/whatsnew/v1.2.0.rst b/doc/source/whatsnew/v1.2.0.rst
index fe80a3b5d6d0c..8aae870d50716 100644
--- a/doc/source/whatsnew/v1.2.0.rst
+++ b/doc/source/whatsnew/v1.2.0.rst
@@ -768,6 +768,10 @@ Plotting
 - Bug in :meth:`DataFrame.plot` and :meth:`Series.plot` was overwriting matplotlib's shared y axes behaviour when no ``sharey`` parameter was passed (:issue:`37942`)
 - Bug in :meth:`DataFrame.plot` was raising a ``TypeError`` with ``ExtensionDtype`` columns (:issue:`32073`)
 
+Styler
+^^^^^^
+
+- Bug in :meth:`Styler.render` HTML was generated incorrectly beacause of formatting error in rowspan attribute, it now matches with w3 syntax. (:issue:`38234`)
 
 Groupby/resample/rolling
 ^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/pandas/io/formats/style.py b/pandas/io/formats/style.py
index 4557c10927a15..6ed31f38893dc 100644
--- a/pandas/io/formats/style.py
+++ b/pandas/io/formats/style.py
@@ -389,7 +389,7 @@ def format_attr(pair):
                 rowspan = idx_lengths.get((c, r), 0)
                 if rowspan > 1:
                     es["attributes"] = [
-                        format_attr({"key": "rowspan", "value": rowspan})
+                        format_attr({"key": "rowspan", "value": f'"{rowspan}"'})
                     ]
                 row_es.append(es)
 
diff --git a/pandas/tests/io/formats/test_style.py b/pandas/tests/io/formats/test_style.py
index 64fe8a7730ae2..0bb422658df25 100644
--- a/pandas/tests/io/formats/test_style.py
+++ b/pandas/tests/io/formats/test_style.py
@@ -1411,7 +1411,7 @@ def test_mi_sparse(self):
             "display_value": "a",
             "is_visible": True,
             "type": "th",
-            "attributes": ["rowspan=2"],
+            "attributes": ['rowspan="2"'],
             "class": "row_heading level0 row0",
             "id": "level0_row0",
         }
@@ -1740,6 +1740,15 @@ def test_colspan_w3(self):
         s = Styler(df, uuid="_", cell_ids=False)
         assert '<th class="col_heading level0 col0" colspan="2">l0</th>' in s.render()
 
+    def test_rowspan_w3(self):
+        # GH 38533
+        df = DataFrame(data=[[1, 2]], index=[["l0", "l0"], ["l1a", "l1b"]])
+        s = Styler(df, uuid="_", cell_ids=False)
+        assert (
+            '<th id="T___level0_row0" class="row_heading '
+            'level0 row0" rowspan="2">l0</th>' in s.render()
+        )
+
     @pytest.mark.parametrize("len_", [1, 5, 32, 33, 100])
     def test_uuid_len(self, len_):
         # GH 36345