diff --git a/gtk3/theme/gtk-widgets.css.em b/gtk3/theme/gtk-widgets.css.em
index 771197d..9b636c8 100644
--- a/gtk3/theme/gtk-widgets.css.em
+++ b/gtk3/theme/gtk-widgets.css.em
@@ -49,6 +49,8 @@ thickness = my_ceil(line_width)
 icon_small = icon_base * 3
 icon_large = icon_base * 5
 
+disabled_opacity = 0.5
+
 }
 
 * {
@@ -583,6 +585,11 @@ SugarPaletteWindowWidget GtkToolButton .button {
     padding: $(toolbutton_padding)px;
 }
 
+GtkToolButton .button:insensitive,
+SugarRadioToolButton .button:insensitive {
+    opacity: $(disabled_opacity);
+}
+
 .toolbar GtkToolButton .button,
 SugarPaletteWindowWidget GtkToolButton .button:prelight {
     padding: $(toolbutton_padding - default_padding)px;