diff --git a/doc/_static/custom.css b/doc/_static/custom.css
index b679d70bbb..732ccf971e 100644
--- a/doc/_static/custom.css
+++ b/doc/_static/custom.css
@@ -3,7 +3,7 @@
 a, a:hover, a:focus, .alert a, .alert .alert-link { color: #ecf0f1; }
 a:visited {color: initial;}
 
-blockquote {
+pre {
     background: #ecf0f1;
 }