diff --git a/browser/themes/winstripe/browser/sanitizeDialog.css b/browser/themes/winstripe/browser/sanitizeDialog.css
index c1b142b68664..2bb2f4a607b5 100644
--- a/browser/themes/winstripe/browser/sanitizeDialog.css
+++ b/browser/themes/winstripe/browser/sanitizeDialog.css
@@ -50,10 +50,7 @@
 /* Progressive disclosure button */
 #detailsExpanderWrapper {
   padding: 0;
-  margin-top: 6px;
-  margin-bottom: 6px;
-  -moz-margin-start: -1px;
-  -moz-margin-end: 0;
+  margin: 6px 0;
 }
 
 .expander-up,