diff --git a/dom/base/nsScreen.cpp b/dom/base/nsScreen.cpp
index f9ae3bb56c..3af597c40f 100644
--- a/dom/base/nsScreen.cpp
+++ b/dom/base/nsScreen.cpp
@@ -65,6 +65,12 @@ nsDeviceContext* nsScreen::GetDeviceContext() const {
 }
 
 CSSIntRect nsScreen::GetRect() {
+  // Check for height and width overrides
+  if (auto height = MaskConfig::GetInt32("screen.height"),
+      width = MaskConfig::GetInt32("screen.width");
+      height && width) {
+    return {0, 0, width.value(), height.value()};
+  }
   // Return window inner rect to prevent fingerprinting.
   if (ShouldResistFingerprinting(RFPTarget::ScreenRect)) {
     return GetTopWindowInnerRectForRFP();
diff --git a/gfx/src/moz.build b/gfx/src/moz.build
index a2b3e60fe5..faa0c113bc 100644
--- a/gfx/src/moz.build
+++ b/gfx/src/moz.build
@@ -95,3 +95,6 @@ FINAL_LIBRARY = "xul"
 if CONFIG["MOZ_WIDGET_TOOLKIT"] == "gtk":
     CXXFLAGS += CONFIG["MOZ_GTK3_CFLAGS"]
     CXXFLAGS += CONFIG["MOZ_PANGO_CFLAGS"]
+
+# DOM Mask
+LOCAL_INCLUDES += ["/camoucfg"]
\ No newline at end of file
diff --git a/gfx/src/nsDeviceContext.cpp b/gfx/src/nsDeviceContext.cpp
index 2bb53010a8..0ff718c0f1 100644
--- a/gfx/src/nsDeviceContext.cpp
+++ b/gfx/src/nsDeviceContext.cpp
@@ -5,6 +5,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "nsDeviceContext.h"
+#include "MaskConfig.hpp"
 #include <algorithm>  // for max
 #include "gfxContext.h"
 #include "gfxImageSurface.h"  // for gfxImageSurface
@@ -388,6 +389,17 @@ void nsDeviceContext::ComputeClientRectUsingScreen(nsRect* outRect) {
 }
 
 void nsDeviceContext::ComputeFullAreaUsingScreen(nsRect* outRect) {
+  // Check for height and width overrides from MaskConfig
+  if (auto height = MaskConfig::GetInt32("screen.height"),
+      width = MaskConfig::GetInt32("screen.width");
+      height && width) {
+    *outRect = LayoutDeviceIntRect::ToAppUnits(
+        LayoutDeviceIntRect(0, 0, width.value(), height.value()),
+        AppUnitsPerDevPixel());
+    mWidth = outRect->Width();
+    mHeight = outRect->Height();
+    return;
+  }
   // if we have more than one screen, we always need to recompute the clientRect
   // because the window may have moved onto a different screen. In the single
   // monitor case, we only need to do the computation if we haven't done it