diff --git a/devtools/shared/css/generated/properties-db.js b/devtools/shared/css/generated/properties-db.js
index 4aa8bae6b1e2..1667304e1a5b 100644
--- a/devtools/shared/css/generated/properties-db.js
+++ b/devtools/shared/css/generated/properties-db.js
@@ -1632,6 +1632,146 @@ exports.CSS_PROPERTIES = {
       "unset"
     ]
   },
+  "-webkit-appearance": {
+    "isInherited": false,
+    "subproperties": [
+      "-moz-appearance"
+    ],
+    "supports": [],
+    "values": [
+      "-moz-gtk-info-bar",
+      "-moz-mac-active-source-list-selection",
+      "-moz-mac-disclosure-button-closed",
+      "-moz-mac-disclosure-button-open",
+      "-moz-mac-fullscreen-button",
+      "-moz-mac-help-button",
+      "-moz-mac-source-list",
+      "-moz-mac-source-list-selection",
+      "-moz-mac-vibrancy-dark",
+      "-moz-mac-vibrancy-light",
+      "-moz-mac-vibrant-titlebar-dark",
+      "-moz-mac-vibrant-titlebar-light",
+      "-moz-menulist-button",
+      "-moz-win-borderless-glass",
+      "-moz-win-browsertabbar-toolbox",
+      "-moz-win-communications-toolbox",
+      "-moz-win-exclude-glass",
+      "-moz-win-glass",
+      "-moz-win-media-toolbox",
+      "-moz-window-button-box",
+      "-moz-window-button-box-maximized",
+      "-moz-window-button-close",
+      "-moz-window-button-maximize",
+      "-moz-window-button-minimize",
+      "-moz-window-button-restore",
+      "-moz-window-frame-bottom",
+      "-moz-window-frame-left",
+      "-moz-window-frame-right",
+      "-moz-window-titlebar",
+      "-moz-window-titlebar-maximized",
+      "button",
+      "button-arrow-down",
+      "button-arrow-next",
+      "button-arrow-previous",
+      "button-arrow-up",
+      "button-bevel",
+      "button-focus",
+      "caret",
+      "checkbox",
+      "checkbox-container",
+      "checkbox-label",
+      "checkmenuitem",
+      "dialog",
+      "dualbutton",
+      "groupbox",
+      "inherit",
+      "initial",
+      "inner-spin-button",
+      "listbox",
+      "listitem",
+      "menuarrow",
+      "menubar",
+      "menucheckbox",
+      "menuimage",
+      "menuitem",
+      "menuitemtext",
+      "menulist",
+      "menulist-button",
+      "menulist-text",
+      "menulist-textfield",
+      "menupopup",
+      "menuradio",
+      "menuseparator",
+      "meterbar",
+      "meterchunk",
+      "none",
+      "number-input",
+      "progressbar",
+      "progressbar-vertical",
+      "progresschunk",
+      "progresschunk-vertical",
+      "radio",
+      "radio-container",
+      "radio-label",
+      "radiomenuitem",
+      "range",
+      "range-thumb",
+      "resizer",
+      "resizerpanel",
+      "scale-horizontal",
+      "scale-vertical",
+      "scalethumb-horizontal",
+      "scalethumb-vertical",
+      "scalethumbend",
+      "scalethumbstart",
+      "scalethumbtick",
+      "scrollbar",
+      "scrollbar-horizontal",
+      "scrollbar-small",
+      "scrollbar-vertical",
+      "scrollbarbutton-down",
+      "scrollbarbutton-left",
+      "scrollbarbutton-right",
+      "scrollbarbutton-up",
+      "scrollbarthumb-horizontal",
+      "scrollbarthumb-vertical",
+      "scrollbartrack-horizontal",
+      "scrollbartrack-vertical",
+      "scrollcorner",
+      "searchfield",
+      "separator",
+      "spinner",
+      "spinner-downbutton",
+      "spinner-textfield",
+      "spinner-upbutton",
+      "splitter",
+      "statusbar",
+      "statusbarpanel",
+      "tab",
+      "tab-scroll-arrow-back",
+      "tab-scroll-arrow-forward",
+      "tabpanel",
+      "tabpanels",
+      "textfield",
+      "textfield-multiline",
+      "toolbar",
+      "toolbarbutton",
+      "toolbarbutton-dropdown",
+      "toolbargripper",
+      "toolbox",
+      "tooltip",
+      "treeheader",
+      "treeheadercell",
+      "treeheadersortarrow",
+      "treeitem",
+      "treeline",
+      "treetwisty",
+      "treetwistyopen",
+      "treeview",
+      "unset",
+      "window"
+    ]
+  },
   "-webkit-backface-visibility": {
     "isInherited": false,
     "subproperties": [
diff --git a/modules/libpref/init/StaticPrefList.h b/modules/libpref/init/StaticPrefList.h
index e39931b2c57d..c543f62e40a1 100644
--- a/modules/libpref/init/StaticPrefList.h
+++ b/modules/libpref/init/StaticPrefList.h
@@ -339,11 +339,17 @@ VARCACHE_PREF(
 )
 
 // Is the '-webkit-appearance' alias for '-moz-appearance' enabled?
+#ifdef EARLY_BETA_OR_EARLIER
+#define PREF_VALUE true
+#else
+#define PREF_VALUE false
+#endif
 VARCACHE_PREF(
   "layout.css.webkit-appearance.enabled",
    layout_css_webkit_appearance_enabled,
-  bool, false
+  bool, PREF_VALUE
 )
+#undef PREF_VALUE
 
 // Pref to control whether @-moz-document rules are enabled in content pages.
 VARCACHE_PREF(