gh-131204: Fix difflib.HtmlDiff may not use monospaced font (#131221)

Wulian233 · blurb-it[bot] · hugovk · web-flow · commit 7fd61607cd28 · 2025-03-14T10:45:33.000Z
Co-authored-by: blurb-it[bot] &lt;43283697+blurb-it[bot]@users.noreply.github.com&gt;
Co-authored-by: Hugo van Kemenade &lt;1324225+hugovk@users.noreply.github.com&gt;
diff --git a/Lib/difflib.py b/Lib/difflib.py
@@ -1633,7 +1633,7 @@ def _line_pair_iterator():
 
 _styles = """
         :root {color-scheme: light dark}
-        table.diff {font-family:Courier; border:medium;}
+        table.diff {font-family: Menlo, Consolas, Monaco, Liberation Mono, Lucida Console, monospace; border:medium}
         .diff_header {background-color:#e0e0e0}
         td.diff_header {text-align:right}
         .diff_next {background-color:#c0c0c0}
diff --git a/Lib/test/test_difflib_expect.html b/Lib/test/test_difflib_expect.html
@@ -10,7 +10,7 @@
     <title></title>
     <style type="text/css">
         :root {color-scheme: light dark}
-        table.diff {font-family:Courier; border:medium;}
+        table.diff {font-family: Menlo, Consolas, Monaco, Liberation Mono, Lucida Console, monospace; border:medium}
         .diff_header {background-color:#e0e0e0}
         td.diff_header {text-align:right}
         .diff_next {background-color:#c0c0c0}
diff --git a/Misc/NEWS.d/next/Library/2025-03-14-09-28-13.gh-issue-131204.wogNEX.rst b/Misc/NEWS.d/next/Library/2025-03-14-09-28-13.gh-issue-131204.wogNEX.rst
@@ -0,0 +1 @@
+Use monospace font from System Font Stack for cross-platform support in  :class:`difflib.HtmlDiff`.

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1 @@`
	`1`	+Use monospace font from System Font Stack for cross-platform support in :class:`difflib.HtmlDiff`.