Index: wp-content/themes/twentyfourteen/rtl.css
===================================================================
--- wp-content/themes/twentyfourteen/rtl.css	(revision 26828)
+++ wp-content/themes/twentyfourteen/rtl.css	(working copy)
@@ -98,8 +98,8 @@
 }
 
 .search-toggle .screen-reader-text {
-	right: auto;
-	left: 0;
+	right: 0; /* Avoid a horizontal scrollbar when the site has a long menu */
+	left: auto;
 }
 
 
Index: wp-content/themes/twentyfourteen/style.css
===================================================================
--- wp-content/themes/twentyfourteen/style.css	(revision 26828)
+++ wp-content/themes/twentyfourteen/style.css	(working copy)
@@ -878,6 +878,10 @@
 	margin-top: 14px;
 }
 
+.search-toggle .screen-reader-text {
+	left: 0; /* Avoid a horizontal scrollbar when the site has a long menu */
+}
+
 .search-box-wrapper {
 	-webkit-box-sizing: border-box;
 	-moz-box-sizing:    border-box;