--- a/browser/themes/linux/preferences/in-content/dialog.css
+++ b/browser/themes/linux/preferences/in-content/dialog.css
@@ -3,17 +3,17 @@
    - You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 %include ../../../shared/incontentprefs/dialog.inc.css
 
 label:not(.menu-text),
 textbox,
 description,
 .tab-text,
-caption > label {
+caption label {
   font-size: 1.11rem;
 }
 
 /* Create a separate rule to unset these styles on .tree-input instead of
    using :not(.tree-input) so the selector specifity doesn't change. */
 textbox.tree-input {
   font-size: unset;
 }

--- a/browser/themes/linux/preferences/in-content/preferences.css
+++ b/browser/themes/linux/preferences/in-content/preferences.css
@@ -5,17 +5,17 @@
 %include ../../../shared/incontentprefs/preferences.inc.css
 
 html *,
 page *,
 window * {
   font-size: 1.11rem;
 }
 
-caption > label:not(.dialogTitle) {
+caption label:not(.dialogTitle) {
   font-size: 1.27rem;
 }
 
 .tip-caption,
 .help-label {
   font-size: 1rem;
 }
 

--- a/browser/themes/osx/preferences/in-content/dialog.css
+++ b/browser/themes/osx/preferences/in-content/dialog.css
@@ -8,17 +8,17 @@ prefwindow,
 .windowDialog {
   font: message-box !important;
 }
 
 label:not(.menu-text),
 textbox,
 description,
 .tab-text,
-caption > label {
+caption label {
   font-size: 1.36rem;
 }
 
 /* Create a separate rule to unset these styles on .tree-input instead of
    using :not(.tree-input) so the selector specifity doesn't change. */
 textbox.tree-input {
   font-size: unset;
 }

--- a/browser/themes/osx/preferences/in-content/preferences.css
+++ b/browser/themes/osx/preferences/in-content/preferences.css
@@ -5,17 +5,17 @@
 %include ../../../shared/incontentprefs/preferences.inc.css
 
 html *,
 page *,
 window * {
   font-size: 1.36rem;
 }
 
-caption > label:not(.dialogTitle) {
+caption label:not(.dialogTitle) {
   font-size: 1.55rem;
 }
 
 .tip-caption,
 .help-label {
   font-size: 1.18rem;
 }
 

--- a/browser/themes/windows/preferences/in-content/dialog.css
+++ b/browser/themes/windows/preferences/in-content/dialog.css
@@ -3,17 +3,17 @@
    - You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 %include ../../../shared/incontentprefs/dialog.inc.css
 
 label:not(.menu-text),
 textbox,
 description,
 .tab-text,
-caption > label {
+caption label {
   font-size: 1.25rem;
 }
 
 /* Create a separate rule to unset these styles on .tree-input instead of
    using :not(.tree-input) so the selector specifity doesn't change. */
 textbox.tree-input {
   font-size: unset;
 }

--- a/browser/themes/windows/preferences/in-content/preferences.css
+++ b/browser/themes/windows/preferences/in-content/preferences.css
@@ -5,17 +5,17 @@
 %include ../../../shared/incontentprefs/preferences.inc.css
 
 html *,
 page *,
 window * {
   font-size: 1.25rem;
 }
 
-caption > label:not(.dialogTitle) {
+caption label:not(.dialogTitle) {
   font-size: 1.42rem;
 }
 
 .tip-caption,
 .help-label {
   font-size: 1.08rem;
 }
 

--- a/toolkit/themes/shared/in-content/common.inc.css
+++ b/toolkit/themes/shared/in-content/common.inc.css
@@ -72,24 +72,24 @@ html|hr {
 }
 
 xul|caption {
   -moz-appearance: none;
   margin: 0;
 }
 
 html|h2,
-xul|caption > xul|checkbox,
-xul|caption > xul|label {
+xul|caption xul|checkbox,
+xul|caption xul|label {
   font-weight: 600;
   line-height: 22px;
 }
 
-xul|caption > xul|checkbox,
-xul|caption > xul|label {
+xul|caption xul|checkbox,
+xul|caption xul|label {
   margin: 0 !important;
 }
 
 *|*.main-content {
   padding: 40px 28px;
   overflow: auto;
 }