diff --git a/widget/gtk/GRefPtr.h b/widget/gtk/GRefPtr.h
index 06d7410ed2e3..197000881136 100644
--- a/widget/gtk/GRefPtr.h
+++ b/widget/gtk/GRefPtr.h
@@ -27,6 +27,7 @@ struct GObjectRefPtrTraits {
 
 GOBJECT_TRAITS(GtkWidget)
 GOBJECT_TRAITS(GFile)
+GOBJECT_TRAITS(GFileMonitor)
 GOBJECT_TRAITS(GMenu)
 GOBJECT_TRAITS(GMenuItem)
 GOBJECT_TRAITS(GSimpleAction)
diff --git a/widget/gtk/nsLookAndFeel.cpp b/widget/gtk/nsLookAndFeel.cpp
index 04213c38f0f5..b9e53c96d40a 100644
--- a/widget/gtk/nsLookAndFeel.cpp
+++ b/widget/gtk/nsLookAndFeel.cpp
@@ -215,6 +215,17 @@ nsLookAndFeel::nsLookAndFeel() {
         },
         this, nullptr);
   }
+  if (IsKdeDesktopEnvironment()) {
+    GUniquePtr<gchar> path(
+        g_strconcat(g_get_user_config_dir(), "/gtk-3.0/colors.css", NULL));
+    mKdeColors = dont_AddRef(g_file_new_for_path(path.get()));
+    mKdeColorsMonitor = dont_AddRef(
+        g_file_monitor_file(mKdeColors.get(), G_FILE_MONITOR_NONE, NULL, NULL));
+    if (mKdeColorsMonitor) {
+      g_signal_connect(mKdeColorsMonitor.get(), "changed",
+                       G_CALLBACK(settings_changed_cb), NULL);
+    }
+  }
 }
 
 nsLookAndFeel::~nsLookAndFeel() {
diff --git a/widget/gtk/nsLookAndFeel.h b/widget/gtk/nsLookAndFeel.h
index f27ea8e4f822..fe9e628f672c 100644
--- a/widget/gtk/nsLookAndFeel.h
+++ b/widget/gtk/nsLookAndFeel.h
@@ -17,6 +17,8 @@ enum WidgetNodeType : int;
 struct _GtkStyle;
 typedef struct _GDBusProxy GDBusProxy;
 typedef struct _GtkCssProvider GtkCssProvider;
+typedef struct _GFile GFile;
+typedef struct _GFileMonitor GFileMonitor;
 
 namespace mozilla {
 enum class StyleGtkThemeFamily : uint8_t;
@@ -162,6 +164,8 @@ class nsLookAndFeel final : public nsXPLookAndFeel {
 
   uint32_t mDBusID = 0;
   RefPtr<GDBusProxy> mDBusSettingsProxy;
+  RefPtr<GFile> mKdeColors;
+  RefPtr<GFileMonitor> mKdeColorsMonitor;
   mozilla::Maybe<ColorScheme> mColorSchemePreference;
   int32_t mCaretBlinkTime = 0;
   int32_t mCaretBlinkCount = -1;