From cb145fce2bed8476be2276436e9b466154422add Mon Sep 17 00:00:00 2001
From: Derek Sharp <dsshar@gmail.com>
Date: Sun, 3 Jul 2022 16:03:52 -0400
Subject: [PATCH 1/3] ENH: Move CSSWarning to error/__init__.py per GH27656

---
 doc/source/reference/testing.rst         |  1 +
 pandas/errors/__init__.py                | 18 ++++++++++++++++++
 pandas/io/formats/css.py                 |  6 +-----
 pandas/tests/io/formats/test_css.py      |  7 +++----
 pandas/tests/io/formats/test_to_excel.py |  2 +-
 pandas/tests/test_errors.py              |  1 +
 6 files changed, 25 insertions(+), 10 deletions(-)

diff --git a/doc/source/reference/testing.rst b/doc/source/reference/testing.rst
index c3ce267ff9dc7..249c2c56cfe57 100644
--- a/doc/source/reference/testing.rst
+++ b/doc/source/reference/testing.rst
@@ -26,6 +26,7 @@ Exceptions and warnings
 
    errors.AbstractMethodError
    errors.AccessorRegistrationWarning
+   errors.CSSWarning
    errors.DataError
    errors.DtypeWarning
    errors.DuplicateLabelError
diff --git a/pandas/errors/__init__.py b/pandas/errors/__init__.py
index 04d52e2c5853c..73173431a0004 100644
--- a/pandas/errors/__init__.py
+++ b/pandas/errors/__init__.py
@@ -395,3 +395,21 @@ def __init__(self, message: str) -> None:
         # attr only exists on Windows, so typing fails on other platforms
         message += f" ({ctypes.WinError()})"  # type: ignore[attr-defined]
         super().__init__(message)
+
+
+class CSSWarning(UserWarning):
+    """
+    Warning is raised when trying to convert styling to a css format and it failing.
+    This can be due to the styling not having an equivalent value or because the
+    styling isn't properly formatted.
+
+    Examples
+    --------
+    >>> df = pd.DataFrame({'A': [1, 1, 1]})
+    >>> df.style.applymap(lambda x: 'background-color: blueGreenRed;')
+    ...         .to_excel('styled.xlsx') # doctest: +SKIP
+    ... # CSSWarning: Unhandled color format: 'blueGreenRed'
+    >>> df.style.applymap(lambda x: 'border: 1px solid red red;')
+    ...         .to_excel('styled.xlsx') # doctest: +SKIP
+    ... # CSSWarning: Too many tokens provided to "border" (expected 1-3)
+    """
diff --git a/pandas/io/formats/css.py b/pandas/io/formats/css.py
index 92dafffc9c3de..778df087d28d8 100644
--- a/pandas/io/formats/css.py
+++ b/pandas/io/formats/css.py
@@ -12,11 +12,7 @@
 )
 import warnings
 
-
-class CSSWarning(UserWarning):
-    """
-    This CSS syntax cannot currently be parsed.
-    """
+from pandas.errors import CSSWarning
 
 
 def _side_expander(prop_fmt: str) -> Callable:
diff --git a/pandas/tests/io/formats/test_css.py b/pandas/tests/io/formats/test_css.py
index c93694481ef53..70c91dd02751a 100644
--- a/pandas/tests/io/formats/test_css.py
+++ b/pandas/tests/io/formats/test_css.py
@@ -1,11 +1,10 @@
 import pytest
 
+from pandas.errors import CSSWarning
+
 import pandas._testing as tm
 
-from pandas.io.formats.css import (
-    CSSResolver,
-    CSSWarning,
-)
+from pandas.io.formats.css import CSSResolver
 
 
 def assert_resolves(css, props, inherited=None):
diff --git a/pandas/tests/io/formats/test_to_excel.py b/pandas/tests/io/formats/test_to_excel.py
index b98fd74643207..7481baaee94f6 100644
--- a/pandas/tests/io/formats/test_to_excel.py
+++ b/pandas/tests/io/formats/test_to_excel.py
@@ -6,11 +6,11 @@
 
 import pytest
 
+from pandas.errors import CSSWarning
 import pandas.util._test_decorators as td
 
 import pandas._testing as tm
 
-from pandas.io.formats.css import CSSWarning
 from pandas.io.formats.excel import (
     CssExcelCell,
     CSSToExcelConverter,
diff --git a/pandas/tests/test_errors.py b/pandas/tests/test_errors.py
index e0ce798fec021..177ff566e347a 100644
--- a/pandas/tests/test_errors.py
+++ b/pandas/tests/test_errors.py
@@ -29,6 +29,7 @@
         "NumExprClobberingError",
         "IndexingError",
         "PyperclipException",
+        "CSSWarning",
     ],
 )
 def test_exception_importable(exc):

From e3ab8713c51e2bab397a4e2a3a5bde5d0cf98043 Mon Sep 17 00:00:00 2001
From: Derek Sharp <dsshar@gmail.com>
Date: Sun, 3 Jul 2022 18:18:25 -0400
Subject: [PATCH 2/3] ENH: fix typo

---
 pandas/errors/__init__.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/errors/__init__.py b/pandas/errors/__init__.py
index 73173431a0004..9eca1c878fa61 100644
--- a/pandas/errors/__init__.py
+++ b/pandas/errors/__init__.py
@@ -399,7 +399,7 @@ def __init__(self, message: str) -> None:
 
 class CSSWarning(UserWarning):
     """
-    Warning is raised when trying to convert styling to a css format and it failing.
+    Warning is raised when trying to convert styling to a css format and it fails.
     This can be due to the styling not having an equivalent value or because the
     styling isn't properly formatted.
 

From 1dec69aae2e080fceb27c76960dc72743a57ce40 Mon Sep 17 00:00:00 2001
From: Derek Sharp <dsshar@gmail.com>
Date: Sun, 3 Jul 2022 18:49:35 -0400
Subject: [PATCH 3/3] ENH: reword sentence

---
 pandas/errors/__init__.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/errors/__init__.py b/pandas/errors/__init__.py
index 9eca1c878fa61..98a9d2b35f09d 100644
--- a/pandas/errors/__init__.py
+++ b/pandas/errors/__init__.py
@@ -399,7 +399,7 @@ def __init__(self, message: str) -> None:
 
 class CSSWarning(UserWarning):
     """
-    Warning is raised when trying to convert styling to a css format and it fails.
+    Warning is raised when converting css styling fails.
     This can be due to the styling not having an equivalent value or because the
     styling isn't properly formatted.