--- a/browser/themes/linux/preferences/in-content/dialog.css
+++ b/browser/themes/linux/preferences/in-content/dialog.css
@@ -4,16 +4,16 @@
 
 %include ../../../shared/incontentprefs/dialog.inc.css
 
 label:not(.menu-text),
 textbox,
 description,
 .tab-text,
 caption > label {
-  font-size: 1.2rem;
+  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
@@ -1,14 +1,29 @@
 /* - This Source Code Form is subject to the terms of the Mozilla Public
    - License, v. 2.0. If a copy of the MPL was not distributed with this file,
    - You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 %include ../../../shared/incontentprefs/preferences.inc.css
 
+html *,
+page *,
+window * {
+  font-size: 1.11rem;
+}
+
+caption > label:not(.dialogTitle) {
+  font-size: 1.27rem;
+}
+
+.tip-caption,
+.help-button {
+  font-size: 1rem;
+}
+
 .treecol-sortdirection {
   /* override the Linux only toolkit rule */
   -moz-appearance: none;
 }
 
 .actionsMenu {
   font-family: "Clear Sans", sans-serif;
   font-size: 1.25rem;

--- a/browser/themes/osx/preferences/in-content/dialog.css
+++ b/browser/themes/osx/preferences/in-content/dialog.css
@@ -9,17 +9,17 @@ prefwindow,
   font: message-box !important;
 }
 
 label:not(.menu-text),
 textbox,
 description,
 .tab-text,
 caption > label {
-  font-size: 1.3rem;
+  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
@@ -1,14 +1,29 @@
 /* - This Source Code Form is subject to the terms of the Mozilla Public
    - License, v. 2.0. If a copy of the MPL was not distributed with this file,
    - You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 %include ../../../shared/incontentprefs/preferences.inc.css
 
+html *,
+page *,
+window * {
+  font-size: 1.36rem;
+}
+
+caption > label:not(.dialogTitle) {
+  font-size: 1.55rem;
+}
+
+.tip-caption,
+.help-button {
+  font-size: 1.18rem;
+}
+
 .actionsMenu > .menulist-label-box > .menulist-icon {
   margin-top: 2px;
   margin-inline-start: 2px;
   margin-inline-end: 8px !important;
 }
 
 #downloadFolder > .fileFieldContentBox {
   padding-inline-start: 3px;

--- a/browser/themes/osx/preferences/preferences.css
+++ b/browser/themes/osx/preferences/preferences.css
@@ -2,29 +2,23 @@
 # -*- Mode: Java; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */
 
 %include ../../../../toolkit/themes/osx/global/shared.inc
 
-@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");
-@namespace html url("http://www.w3.org/1999/xhtml");
-
 .windowDialog {
   padding: 12px;
   font: -moz-dialog;
 }
 
 /* ----- APPLICATIONS PREFPANE ----- */
 description {
-  font: small-caption;
-  font-weight: normal;
-  line-height: 1.3em;
   margin-bottom: 4px !important;
 }
 
 prefpane .groupbox-body {
   -moz-appearance: none;
   padding: 8px 4px 4px 4px;
 }
 

--- a/browser/themes/windows/preferences/in-content/dialog.css
+++ b/browser/themes/windows/preferences/in-content/dialog.css
@@ -4,16 +4,16 @@
 
 %include ../../../shared/incontentprefs/dialog.inc.css
 
 label:not(.menu-text),
 textbox,
 description,
 .tab-text,
 caption > label {
-  font-size: 1.2rem;
+  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
@@ -1,14 +1,29 @@
 /* - This Source Code Form is subject to the terms of the Mozilla Public
    - License, v. 2.0. If a copy of the MPL was not distributed with this file,
    - You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 %include ../../../shared/incontentprefs/preferences.inc.css
 
+html *,
+page *,
+window * {
+  font-size: 1.25rem;
+}
+
+caption > label:not(.dialogTitle) {
+  font-size: 1.42rem;
+}
+
+.tip-caption,
+.help-button {
+  font-size: 1.08rem;
+}
+
 .actionsMenu > .menulist-label-box > .menulist-icon {
   margin-inline-end: 9px;
 }
 
 textbox + button,
 filefield + button {
   margin-inline-start: -4px;
   margin-top: 4px;

--- a/toolkit/themes/linux/global/in-content/common.css
+++ b/toolkit/themes/linux/global/in-content/common.css
@@ -112,30 +112,15 @@ xul|treechildren::-moz-tree-row(multicol
 xul|treechildren::-moz-tree-row(hover) {
   background-color: var(--in-content-item-hover);
 }
 
 xul|treechildren::-moz-tree-row(selected) {
   background-color: var(--in-content-item-selected);
 }
 
-html|html *,
-xul|page *,
-xul|window * {
-  font-size: 1.11rem;
-}
-
 *|*.header-name {
   font-size: 1.64rem;
 }
 
 *|*.category-name {
   font-size: 1.19rem;
 }
-
-xul|caption > xul|label:not(.dialogTitle) {
-  font-size: 1.27rem;
-}
-
-.tip-caption,
-.help-button {
-  font-size: 1rem;
-}

--- a/toolkit/themes/osx/global/in-content/common.css
+++ b/toolkit/themes/osx/global/in-content/common.css
@@ -10,23 +10,16 @@ xul|tabs {
   padding-left: 0;
 }
 
 xul|tab[visuallyselected] {
   text-shadow: none;
 }
 
 xul|button,
-html|button,
-xul|colorpicker[type="button"],
-xul|menulist {
-  margin-top: 3px;
-}
-
-xul|button,
 html|button {
   /* use the same margin of other elements for the alignment */
   margin-left: 4px;
   margin-right: 4px;
 }
 
 xul|button[dlgtype="help"] {
   -moz-appearance: none;
@@ -72,16 +65,17 @@ xul|*.radio-icon {
 }
 
 xul|*.numberbox-input-box {
   -moz-appearance: none;
   border-width: 0;
 }
 
 xul|description {
+  font-size: 1.25rem;
   line-height: 22px;
 }
 
 xul|*.text-link:-moz-focusring {
   color: var(--in-content-link-highlight);
   text-decoration: underline;
   box-shadow: none;
 }
@@ -124,30 +118,15 @@ xul|*.spinbuttons-button > xul|*.button-
   display: none;
 }
 
 xul|textbox[type="search"]:not([searchbutton]) > .textbox-input-box > .textbox-search-sign {
   list-style-image: url(chrome://global/skin/icons/search-textbox.svg);
   margin-inline-end: 5px;
 }
 
-html|html *,
-xul|page *,
-xul|window * {
-  font-size: 1.36rem;
-}
-
 *|*.header-name {
   font-size: 2rem;
 }
 
 *|*.category-name {
   font-size: 1.45rem;
 }
-
-xul|caption > xul|label:not(.dialogTitle) {
-  font-size: 1.55rem;
-}
-
-.tip-caption,
-.help-button {
-  font-size: 1.18rem;
-}

--- a/toolkit/themes/shared/in-content/common.inc.css
+++ b/toolkit/themes/shared/in-content/common.inc.css
@@ -169,18 +169,16 @@ xul|*.tab-text {
   font-size: 1.3rem;
   line-height: 22px;
 }
 
 /* html buttons */
 
 html|button {
   padding: 3px;
-  /* override forms.css */
-  font: inherit;
 }
 
 /* xul buttons and menulists */
 
 *|button,
 html|select,
 xul|colorpicker[type="button"],
 xul|menulist {

--- a/toolkit/themes/windows/global/in-content/common.css
+++ b/toolkit/themes/windows/global/in-content/common.css
@@ -73,30 +73,15 @@ html|input[type="checkbox"]:-moz-focusri
     an existing high-contrast border that uses the background color */
 @media (-moz-windows-default-theme: 0) {
   xul|treechildren::-moz-tree-row(selected),
   xul|listbox xul|listitem[selected="true"] {
      border: 2px dotted Highlight;
   }
 }
 
-html|html *,
-xul|page *,
-xul|window * {
-  font-size: 1.25rem;
-}
-
 *|*.header-name {
   font-size: 1.83rem;
 }
 
 *|*.category-name {
   font-size: 1.33rem;
 }
-
-xul|caption > xul|label:not(.dialogTitle) {
-  font-size: 1.42rem;
-}
-
-.tip-caption,
-.help-button {
-  font-size: 1.08rem;
-}