diff --git a/docs/_static/css/custom.css b/docs/_static/css/custom.css
index d2c9c86e7b2e..6d0896d8088e 100644
--- a/docs/_static/css/custom.css
+++ b/docs/_static/css/custom.css
@@ -155,12 +155,6 @@ span.pre,
 pre {
     /* css-3 */
     white-space: pre-wrap;
-    /* Mozilla, since 1999 */
-    white-space: -moz-pre-wrap;
-    /* Opera 4-6 */
-    white-space: -pre-wrap;
-    /* Opera 7 */
-    white-space: -o-pre-wrap;
     word-wrap: break-word;
     font-family: 'Overpass Mono', monospace;
 }