diff --git a/docs/theme/nature/static/nature.css_t b/docs/theme/nature/static/nature.css_t
--- a/docs/theme/nature/static/nature.css_t
+++ b/docs/theme/nature/static/nature.css_t
@@ -216,8 +216,7 @@ pre {
     border: 1px solid #C6C9CB;
     font-size: 1.2em;
     margin: 1.5em 0 1.5em 0;
-    -webkit-box-shadow: 1px 1px 1px #d8d8d8;
-    -moz-box-shadow: 1px 1px 1px #d8d8d8;
+    box-shadow: 1px 1px 1px #d8d8d8;
 }
  
 tt {