diff --git a/docs/extra.css b/docs/extra.css
index e953fa14c..da963daf8 100644
--- a/docs/extra.css
+++ b/docs/extra.css
@@ -3,6 +3,7 @@ img {
     display: block;
     margin-left: auto;
     margin-right: auto;
+    background-color: rgba(255, 255, 255, 0.64);
 }
 
 /* Tables */