diff --git a/rtdata/themes/RawTherapee-GTK3-20_.css b/rtdata/themes/RawTherapee-GTK3-20_.css
index c1768f913..f661198af 100644
--- a/rtdata/themes/RawTherapee-GTK3-20_.css
+++ b/rtdata/themes/RawTherapee-GTK3-20_.css
@@ -187,24 +187,37 @@ button  {
     min-width: 5px;
     background-image: linear-gradient(#343434, #2E2E2E, #292929);
 }
+
+/* Curve mode buttons and drop-downs */
+button:checked.Left, button:checked.Left + button {
+    background-image: linear-gradient(to bottom, rgba(100,100,100,.3), rgba(30,30,30,.3));
+    background-color: #585858;
+}
+
 button.flat  {
     background-image: none;
 }
+
 button.flat:checked {
     background-image:  linear-gradient(#343434, #2E2E2E, #292929);
 }
+
 checkbutton > check {
     background-image: linear-gradient(#343434, #2E2E2E, #292929);
 }
+
 radiobutton > radio {
     background-image: linear-gradient(#343434, #2E2E2E, #292929);
 }
+
 button:hover , button.flat:hover, checkbutton:hover > check, radiobutton:hover > radio {
     background-image: linear-gradient(shade(#343434,1.3), shade(#2E2E2E,1.3), shade(#292929,1.3));
 }
+
 button.popupbutton-arrow {
     min-width: 18px;
 }
+
 /* Save, Cancel, OK ... buttons */
 .dialog-action-area button {
     min-height: 24px;