diff --git a/doc_src/python_docs_theme/static/pydoctheme.css b/doc_src/python_docs_theme/static/pydoctheme.css
index 66b5147be..f8f3ad99b 100644
--- a/doc_src/python_docs_theme/static/pydoctheme.css
+++ b/doc_src/python_docs_theme/static/pydoctheme.css
@@ -467,6 +467,10 @@ div.body .internal.reference:link {
         color: inherit;
     }
 
+    div.body pre {
+        border: 1px solid #536;
+    }
+
     .footnote, .footnote-reference {
         background-color: #101020;
     }