From 72b0c4143e385309a968cf2e7b8df60c20f35e9f Mon Sep 17 00:00:00 2001
From: mrinalcodez <soodman4@gmail.com>
Date: Sat, 15 Nov 2025 05:50:32 +0530
Subject: [PATCH 1/2] 2.3.x

---
 pandas/io/formats/css.py | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/pandas/io/formats/css.py b/pandas/io/formats/css.py
index 0f1a7302aa808..35eb045869326 100644
--- a/pandas/io/formats/css.py
+++ b/pandas/io/formats/css.py
@@ -19,6 +19,16 @@
         Iterator,
     )
 
+def _lowercase_outside_quotes(value: str) -> str:
+    parts = re.split(r'(".*?")', value)
+    new_parts = []
+    for part in parts:
+        if part.startswith('"') and part.endswith('"'):
+            new_parts.append(part)  # preserve case
+        else:
+            new_parts.append(part.lower())
+    return ''.join(new_parts)
+
 
 def _side_expander(prop_fmt: str) -> Callable:
     """
@@ -391,7 +401,7 @@ def _error() -> str:
     def atomize(self, declarations: Iterable) -> Generator[tuple[str, str]]:
         for prop, value in declarations:
             prop = prop.lower()
-            value = value.lower()
+            value = _lowercase_outside_quotes(value)
             if prop in self.CSS_EXPANSIONS:
                 expand = self.CSS_EXPANSIONS[prop]
                 yield from expand(self, prop, value)
@@ -414,7 +424,8 @@ def parse(self, declarations_str: str) -> Iterator[tuple[str, str]]:
             prop, sep, val = decl.partition(":")
             prop = prop.strip().lower()
             # TODO: don't lowercase case sensitive parts of values (strings)
-            val = val.strip().lower()
+            raw_val = val.strip()
+            val = _lowercase_outside_quotes(raw_val)
             if sep:
                 yield prop, val
             else:

From c106c5bef2352eb666bd872b3e34fd19d4b0ab77 Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Sat, 15 Nov 2025 16:20:32 +0000
Subject: [PATCH 2/2] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 pandas/io/formats/css.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/pandas/io/formats/css.py b/pandas/io/formats/css.py
index 35eb045869326..4a6c2e36156f6 100644
--- a/pandas/io/formats/css.py
+++ b/pandas/io/formats/css.py
@@ -19,6 +19,7 @@
         Iterator,
     )
 
+
 def _lowercase_outside_quotes(value: str) -> str:
     parts = re.split(r'(".*?")', value)
     new_parts = []
@@ -27,7 +28,7 @@ def _lowercase_outside_quotes(value: str) -> str:
             new_parts.append(part)  # preserve case
         else:
             new_parts.append(part.lower())
-    return ''.join(new_parts)
+    return "".join(new_parts)
 
 
 def _side_expander(prop_fmt: str) -> Callable: