--- a/browser/themes/linux/syncedtabs/sidebar.css
+++ b/browser/themes/linux/syncedtabs/sidebar.css
@@ -30,25 +30,25 @@ html {
 
 .textbox-search-clear {
   background-image: url(moz-icon://stock/gtk-clear?size=menu);
   background-repeat: no-repeat;
   width: 16px;
   height: 16px;
 }
 
-.search-box > .textbox-input-box > .textbox-input {
+.search-box > .textbox-input-box {
   background-image: url(chrome://global/skin/icons/search-textbox.svg);
   background-repeat: no-repeat;
   background-size: 12px 12px;
   background-position: left center;
-  text-indent: 14px;
+  padding-inline-start: 14px;
 }
 
-.search-box > .textbox-input-box > .textbox-input:-moz-locale-dir(rtl) {
+.search-box > .textbox-input-box:-moz-locale-dir(rtl) {
   background-position: right center;
 }
 
 .textbox-search-clear:not([disabled]) {
   cursor: pointer;
 }
 
 .item.client .item-twisty-container {

--- a/browser/themes/windows/syncedtabs/sidebar.css
+++ b/browser/themes/windows/syncedtabs/sidebar.css
@@ -22,25 +22,25 @@
   -moz-appearance: textfield;
   cursor: text;
   margin: 4px;
   padding: 2px 2px 3px;
   padding-inline-start: 4px;
   color: -moz-FieldText;
 }
 
-.search-box > .textbox-input-box > .textbox-input {
+.search-box > .textbox-input-box {
   background-image: url(chrome://global/skin/icons/search-textbox.svg);
   background-repeat: no-repeat;
   background-size: 12px 12px;
   background-position: left center;
-  text-indent: 14px;
+  padding-inline-start: 14px;
 }
 
-.search-box > .textbox-input-box > .textbox-input:-moz-locale-dir(rtl) {
+.search-box > .textbox-input-box:-moz-locale-dir(rtl) {
   background-position: right center;
 }
 
 .textbox-search-clear {
   width: 16px;
   height: 16px;
   background-image: url(chrome://global/skin/icons/Search-close.png);
   background-repeat: no-repeat;