diff --git a/common/gtk-3.0/3.20/gtk-dark.css b/common/gtk-3.0/3.20/gtk-dark.css
index 9d77391..05f4f17 100644
--- a/common/gtk-3.0/3.20/gtk-dark.css
+++ b/common/gtk-3.0/3.20/gtk-dark.css
@@ -3312,7 +3312,9 @@ button.documents-favorite:active:hover {
 
 .gnome-panel-menu-bar, .gnome-panel-menu-bar menubar,
 .mate-panel-menu-bar,
-.mate-panel-menu-bar menubar {
+.mate-panel-menu-bar menubar,
+panel-toplevel.background,
+panel-toplevel.background menubar {
   background-color: rgba(43, 46, 55, 0.95); }
 
 .gnome-panel-menu-bar menubar,
@@ -3320,7 +3322,10 @@ button.documents-favorite:active:hover {
 .gnome-panel-menu-bar #PanelApplet image,
 .mate-panel-menu-bar menubar,
 .mate-panel-menu-bar #PanelApplet label,
-.mate-panel-menu-bar #PanelApplet image {
+.mate-panel-menu-bar #PanelApplet image,
+panel-toplevel.background menubar,
+panel-toplevel.background #PanelApplet label,
+panel-toplevel.background #PanelApplet image {
   color: #BAC3CF; }
 
 .gnome-panel-menu-bar button label, .gnome-panel-menu-bar button image,
@@ -3329,23 +3334,31 @@ button.documents-favorite:active:hover {
 .mate-panel-menu-bar button label,
 .mate-panel-menu-bar button image,
 .mate-panel-menu-bar #tasklist-button label,
-.mate-panel-menu-bar #tasklist-button image {
+.mate-panel-menu-bar #tasklist-button image,
+panel-toplevel.background button label,
+panel-toplevel.background button image,
+panel-toplevel.background #tasklist-button label,
+panel-toplevel.background #tasklist-button image {
   color: inherit; }
 
 .gnome-panel-menu-bar .wnck-pager,
-.mate-panel-menu-bar .wnck-pager {
+.mate-panel-menu-bar .wnck-pager,
+panel-toplevel.background .wnck-pager {
   color: #5d6268;
   background-color: rgba(20, 22, 27, 0.95); }
   .gnome-panel-menu-bar .wnck-pager:hover,
-  .mate-panel-menu-bar .wnck-pager:hover {
+  .mate-panel-menu-bar .wnck-pager:hover,
+  panel-toplevel.background .wnck-pager:hover {
     background-color: rgba(54, 58, 70, 0.95); }
   .gnome-panel-menu-bar .wnck-pager:selected,
-  .mate-panel-menu-bar .wnck-pager:selected {
+  .mate-panel-menu-bar .wnck-pager:selected,
+  panel-toplevel.background .wnck-pager:selected {
     color: #a9caf1;
     background-color: #5294e2; }
 
 .gnome-panel-menu-bar na-tray-applet,
-.mate-panel-menu-bar na-tray-applet {
+.mate-panel-menu-bar na-tray-applet,
+panel-toplevel.background na-tray-applet {
   -NaTrayApplet-icon-padding: 0;
   -NaTrayApplet-icon-size: 16px; }
 
@@ -3368,18 +3381,22 @@ button.documents-favorite:active:hover {
     box-shadow: inset 0 -2px #5294e2; }
 
 .gnome-panel-menu-bar button:not(#tasklist-button),
-.mate-panel-menu-bar button:not(#tasklist-button), .xfce4-panel.panel button.flat, .xfce4-panel.panel button.sidebar-button {
+.mate-panel-menu-bar button:not(#tasklist-button),
+panel-toplevel.background button:not(#tasklist-button), .xfce4-panel.panel button.flat, .xfce4-panel.panel button.sidebar-button {
   color: #BAC3CF;
   border-radius: 0;
   border: none;
   background-color: rgba(43, 46, 55, 0); }
   .gnome-panel-menu-bar button:hover:not(#tasklist-button),
-  .mate-panel-menu-bar button:hover:not(#tasklist-button), .xfce4-panel.panel button.flat:hover, .xfce4-panel.panel button.sidebar-button:hover {
+  .mate-panel-menu-bar button:hover:not(#tasklist-button),
+  panel-toplevel.background button:hover:not(#tasklist-button), .xfce4-panel.panel button.flat:hover, .xfce4-panel.panel button.sidebar-button:hover {
     border: none;
     background-color: rgba(65, 70, 84, 0.95); }
   .gnome-panel-menu-bar button:active:not(#tasklist-button),
-  .mate-panel-menu-bar button:active:not(#tasklist-button), .xfce4-panel.panel button.flat:active, .xfce4-panel.panel button.sidebar-button:active, .gnome-panel-menu-bar button:checked:not(#tasklist-button),
-  .mate-panel-menu-bar button:checked:not(#tasklist-button), .xfce4-panel.panel button.flat:checked, .xfce4-panel.panel button.sidebar-button:checked {
+  .mate-panel-menu-bar button:active:not(#tasklist-button),
+  panel-toplevel.background button:active:not(#tasklist-button), .xfce4-panel.panel button.flat:active, .xfce4-panel.panel button.sidebar-button:active, .gnome-panel-menu-bar button:checked:not(#tasklist-button),
+  .mate-panel-menu-bar button:checked:not(#tasklist-button),
+  panel-toplevel.background button:checked:not(#tasklist-button), .xfce4-panel.panel button.flat:checked, .xfce4-panel.panel button.sidebar-button:checked {
     color: #ffffff;
     border: none;
     background-color: #5294e2; }
diff --git a/common/gtk-3.0/3.20/gtk-darker.css b/common/gtk-3.0/3.20/gtk-darker.css
index 746bd1d..adb7231 100644
--- a/common/gtk-3.0/3.20/gtk-darker.css
+++ b/common/gtk-3.0/3.20/gtk-darker.css
@@ -3311,7 +3311,9 @@ button.documents-favorite:active:hover {
 
 .gnome-panel-menu-bar, .gnome-panel-menu-bar menubar,
 .mate-panel-menu-bar,
-.mate-panel-menu-bar menubar {
+.mate-panel-menu-bar menubar,
+panel-toplevel.background,
+panel-toplevel.background menubar {
   background-color: rgba(43, 46, 55, 0.95); }
 
 .gnome-panel-menu-bar menubar,
@@ -3319,7 +3321,10 @@ button.documents-favorite:active:hover {
 .gnome-panel-menu-bar #PanelApplet image,
 .mate-panel-menu-bar menubar,
 .mate-panel-menu-bar #PanelApplet label,
-.mate-panel-menu-bar #PanelApplet image {
+.mate-panel-menu-bar #PanelApplet image,
+panel-toplevel.background menubar,
+panel-toplevel.background #PanelApplet label,
+panel-toplevel.background #PanelApplet image {
   color: #BAC3CF; }
 
 .gnome-panel-menu-bar button label, .gnome-panel-menu-bar button image,
@@ -3328,23 +3333,31 @@ button.documents-favorite:active:hover {
 .mate-panel-menu-bar button label,
 .mate-panel-menu-bar button image,
 .mate-panel-menu-bar #tasklist-button label,
-.mate-panel-menu-bar #tasklist-button image {
+.mate-panel-menu-bar #tasklist-button image,
+panel-toplevel.background button label,
+panel-toplevel.background button image,
+panel-toplevel.background #tasklist-button label,
+panel-toplevel.background #tasklist-button image {
   color: inherit; }
 
 .gnome-panel-menu-bar .wnck-pager,
-.mate-panel-menu-bar .wnck-pager {
+.mate-panel-menu-bar .wnck-pager,
+panel-toplevel.background .wnck-pager {
   color: #5d6268;
   background-color: rgba(20, 22, 27, 0.95); }
   .gnome-panel-menu-bar .wnck-pager:hover,
-  .mate-panel-menu-bar .wnck-pager:hover {
+  .mate-panel-menu-bar .wnck-pager:hover,
+  panel-toplevel.background .wnck-pager:hover {
     background-color: rgba(54, 58, 70, 0.95); }
   .gnome-panel-menu-bar .wnck-pager:selected,
-  .mate-panel-menu-bar .wnck-pager:selected {
+  .mate-panel-menu-bar .wnck-pager:selected,
+  panel-toplevel.background .wnck-pager:selected {
     color: #a9caf1;
     background-color: #5294e2; }
 
 .gnome-panel-menu-bar na-tray-applet,
-.mate-panel-menu-bar na-tray-applet {
+.mate-panel-menu-bar na-tray-applet,
+panel-toplevel.background na-tray-applet {
   -NaTrayApplet-icon-padding: 0;
   -NaTrayApplet-icon-size: 16px; }
 
@@ -3367,18 +3380,22 @@ button.documents-favorite:active:hover {
     box-shadow: inset 0 -2px #5294e2; }
 
 .gnome-panel-menu-bar button:not(#tasklist-button),
-.mate-panel-menu-bar button:not(#tasklist-button), .xfce4-panel.panel button.flat, .xfce4-panel.panel button.sidebar-button {
+.mate-panel-menu-bar button:not(#tasklist-button),
+panel-toplevel.background button:not(#tasklist-button), .xfce4-panel.panel button.flat, .xfce4-panel.panel button.sidebar-button {
   color: #BAC3CF;
   border-radius: 0;
   border: none;
   background-color: rgba(43, 46, 55, 0); }
   .gnome-panel-menu-bar button:hover:not(#tasklist-button),
-  .mate-panel-menu-bar button:hover:not(#tasklist-button), .xfce4-panel.panel button.flat:hover, .xfce4-panel.panel button.sidebar-button:hover {
+  .mate-panel-menu-bar button:hover:not(#tasklist-button),
+  panel-toplevel.background button:hover:not(#tasklist-button), .xfce4-panel.panel button.flat:hover, .xfce4-panel.panel button.sidebar-button:hover {
     border: none;
     background-color: rgba(65, 70, 84, 0.95); }
   .gnome-panel-menu-bar button:active:not(#tasklist-button),
-  .mate-panel-menu-bar button:active:not(#tasklist-button), .xfce4-panel.panel button.flat:active, .xfce4-panel.panel button.sidebar-button:active, .gnome-panel-menu-bar button:checked:not(#tasklist-button),
-  .mate-panel-menu-bar button:checked:not(#tasklist-button), .xfce4-panel.panel button.flat:checked, .xfce4-panel.panel button.sidebar-button:checked {
+  .mate-panel-menu-bar button:active:not(#tasklist-button),
+  panel-toplevel.background button:active:not(#tasklist-button), .xfce4-panel.panel button.flat:active, .xfce4-panel.panel button.sidebar-button:active, .gnome-panel-menu-bar button:checked:not(#tasklist-button),
+  .mate-panel-menu-bar button:checked:not(#tasklist-button),
+  panel-toplevel.background button:checked:not(#tasklist-button), .xfce4-panel.panel button.flat:checked, .xfce4-panel.panel button.sidebar-button:checked {
     color: #ffffff;
     border: none;
     background-color: #5294e2; }
diff --git a/common/gtk-3.0/3.20/gtk-solid-dark.css b/common/gtk-3.0/3.20/gtk-solid-dark.css
index eb790b2..eca4ec2 100644
--- a/common/gtk-3.0/3.20/gtk-solid-dark.css
+++ b/common/gtk-3.0/3.20/gtk-solid-dark.css
@@ -3312,7 +3312,9 @@ button.documents-favorite:active:hover {
 
 .gnome-panel-menu-bar, .gnome-panel-menu-bar menubar,
 .mate-panel-menu-bar,
-.mate-panel-menu-bar menubar {
+.mate-panel-menu-bar menubar,
+panel-toplevel.background,
+panel-toplevel.background menubar {
   background-color: #2b2e37; }
 
 .gnome-panel-menu-bar menubar,
@@ -3320,7 +3322,10 @@ button.documents-favorite:active:hover {
 .gnome-panel-menu-bar #PanelApplet image,
 .mate-panel-menu-bar menubar,
 .mate-panel-menu-bar #PanelApplet label,
-.mate-panel-menu-bar #PanelApplet image {
+.mate-panel-menu-bar #PanelApplet image,
+panel-toplevel.background menubar,
+panel-toplevel.background #PanelApplet label,
+panel-toplevel.background #PanelApplet image {
   color: #BAC3CF; }
 
 .gnome-panel-menu-bar button label, .gnome-panel-menu-bar button image,
@@ -3329,23 +3334,31 @@ button.documents-favorite:active:hover {
 .mate-panel-menu-bar button label,
 .mate-panel-menu-bar button image,
 .mate-panel-menu-bar #tasklist-button label,
-.mate-panel-menu-bar #tasklist-button image {
+.mate-panel-menu-bar #tasklist-button image,
+panel-toplevel.background button label,
+panel-toplevel.background button image,
+panel-toplevel.background #tasklist-button label,
+panel-toplevel.background #tasklist-button image {
   color: inherit; }
 
 .gnome-panel-menu-bar .wnck-pager,
-.mate-panel-menu-bar .wnck-pager {
+.mate-panel-menu-bar .wnck-pager,
+panel-toplevel.background .wnck-pager {
   color: #5d6268;
   background-color: #14161b; }
   .gnome-panel-menu-bar .wnck-pager:hover,
-  .mate-panel-menu-bar .wnck-pager:hover {
+  .mate-panel-menu-bar .wnck-pager:hover,
+  panel-toplevel.background .wnck-pager:hover {
     background-color: #363a46; }
   .gnome-panel-menu-bar .wnck-pager:selected,
-  .mate-panel-menu-bar .wnck-pager:selected {
+  .mate-panel-menu-bar .wnck-pager:selected,
+  panel-toplevel.background .wnck-pager:selected {
     color: #a9caf1;
     background-color: #5294e2; }
 
 .gnome-panel-menu-bar na-tray-applet,
-.mate-panel-menu-bar na-tray-applet {
+.mate-panel-menu-bar na-tray-applet,
+panel-toplevel.background na-tray-applet {
   -NaTrayApplet-icon-padding: 0;
   -NaTrayApplet-icon-size: 16px; }
 
@@ -3368,18 +3381,22 @@ button.documents-favorite:active:hover {
     box-shadow: inset 0 -2px #5294e2; }
 
 .gnome-panel-menu-bar button:not(#tasklist-button),
-.mate-panel-menu-bar button:not(#tasklist-button), .xfce4-panel.panel button.flat, .xfce4-panel.panel button.sidebar-button {
+.mate-panel-menu-bar button:not(#tasklist-button),
+panel-toplevel.background button:not(#tasklist-button), .xfce4-panel.panel button.flat, .xfce4-panel.panel button.sidebar-button {
   color: #BAC3CF;
   border-radius: 0;
   border: none;
   background-color: rgba(43, 46, 55, 0); }
   .gnome-panel-menu-bar button:hover:not(#tasklist-button),
-  .mate-panel-menu-bar button:hover:not(#tasklist-button), .xfce4-panel.panel button.flat:hover, .xfce4-panel.panel button.sidebar-button:hover {
+  .mate-panel-menu-bar button:hover:not(#tasklist-button),
+  panel-toplevel.background button:hover:not(#tasklist-button), .xfce4-panel.panel button.flat:hover, .xfce4-panel.panel button.sidebar-button:hover {
     border: none;
     background-color: #414654; }
   .gnome-panel-menu-bar button:active:not(#tasklist-button),
-  .mate-panel-menu-bar button:active:not(#tasklist-button), .xfce4-panel.panel button.flat:active, .xfce4-panel.panel button.sidebar-button:active, .gnome-panel-menu-bar button:checked:not(#tasklist-button),
-  .mate-panel-menu-bar button:checked:not(#tasklist-button), .xfce4-panel.panel button.flat:checked, .xfce4-panel.panel button.sidebar-button:checked {
+  .mate-panel-menu-bar button:active:not(#tasklist-button),
+  panel-toplevel.background button:active:not(#tasklist-button), .xfce4-panel.panel button.flat:active, .xfce4-panel.panel button.sidebar-button:active, .gnome-panel-menu-bar button:checked:not(#tasklist-button),
+  .mate-panel-menu-bar button:checked:not(#tasklist-button),
+  panel-toplevel.background button:checked:not(#tasklist-button), .xfce4-panel.panel button.flat:checked, .xfce4-panel.panel button.sidebar-button:checked {
     color: #ffffff;
     border: none;
     background-color: #5294e2; }
diff --git a/common/gtk-3.0/3.20/gtk-solid-darker.css b/common/gtk-3.0/3.20/gtk-solid-darker.css
index 238043c..1bbf62f 100644
--- a/common/gtk-3.0/3.20/gtk-solid-darker.css
+++ b/common/gtk-3.0/3.20/gtk-solid-darker.css
@@ -3311,7 +3311,9 @@ button.documents-favorite:active:hover {
 
 .gnome-panel-menu-bar, .gnome-panel-menu-bar menubar,
 .mate-panel-menu-bar,
-.mate-panel-menu-bar menubar {
+.mate-panel-menu-bar menubar,
+panel-toplevel.background,
+panel-toplevel.background menubar {
   background-color: #2b2e37; }
 
 .gnome-panel-menu-bar menubar,
@@ -3319,7 +3321,10 @@ button.documents-favorite:active:hover {
 .gnome-panel-menu-bar #PanelApplet image,
 .mate-panel-menu-bar menubar,
 .mate-panel-menu-bar #PanelApplet label,
-.mate-panel-menu-bar #PanelApplet image {
+.mate-panel-menu-bar #PanelApplet image,
+panel-toplevel.background menubar,
+panel-toplevel.background #PanelApplet label,
+panel-toplevel.background #PanelApplet image {
   color: #BAC3CF; }
 
 .gnome-panel-menu-bar button label, .gnome-panel-menu-bar button image,
@@ -3328,23 +3333,31 @@ button.documents-favorite:active:hover {
 .mate-panel-menu-bar button label,
 .mate-panel-menu-bar button image,
 .mate-panel-menu-bar #tasklist-button label,
-.mate-panel-menu-bar #tasklist-button image {
+.mate-panel-menu-bar #tasklist-button image,
+panel-toplevel.background button label,
+panel-toplevel.background button image,
+panel-toplevel.background #tasklist-button label,
+panel-toplevel.background #tasklist-button image {
   color: inherit; }
 
 .gnome-panel-menu-bar .wnck-pager,
-.mate-panel-menu-bar .wnck-pager {
+.mate-panel-menu-bar .wnck-pager,
+panel-toplevel.background .wnck-pager {
   color: #5d6268;
   background-color: #14161b; }
   .gnome-panel-menu-bar .wnck-pager:hover,
-  .mate-panel-menu-bar .wnck-pager:hover {
+  .mate-panel-menu-bar .wnck-pager:hover,
+  panel-toplevel.background .wnck-pager:hover {
     background-color: #363a46; }
   .gnome-panel-menu-bar .wnck-pager:selected,
-  .mate-panel-menu-bar .wnck-pager:selected {
+  .mate-panel-menu-bar .wnck-pager:selected,
+  panel-toplevel.background .wnck-pager:selected {
     color: #a9caf1;
     background-color: #5294e2; }
 
 .gnome-panel-menu-bar na-tray-applet,
-.mate-panel-menu-bar na-tray-applet {
+.mate-panel-menu-bar na-tray-applet,
+panel-toplevel.background na-tray-applet {
   -NaTrayApplet-icon-padding: 0;
   -NaTrayApplet-icon-size: 16px; }
 
@@ -3367,18 +3380,22 @@ button.documents-favorite:active:hover {
     box-shadow: inset 0 -2px #5294e2; }
 
 .gnome-panel-menu-bar button:not(#tasklist-button),
-.mate-panel-menu-bar button:not(#tasklist-button), .xfce4-panel.panel button.flat, .xfce4-panel.panel button.sidebar-button {
+.mate-panel-menu-bar button:not(#tasklist-button),
+panel-toplevel.background button:not(#tasklist-button), .xfce4-panel.panel button.flat, .xfce4-panel.panel button.sidebar-button {
   color: #BAC3CF;
   border-radius: 0;
   border: none;
   background-color: rgba(43, 46, 55, 0); }
   .gnome-panel-menu-bar button:hover:not(#tasklist-button),
-  .mate-panel-menu-bar button:hover:not(#tasklist-button), .xfce4-panel.panel button.flat:hover, .xfce4-panel.panel button.sidebar-button:hover {
+  .mate-panel-menu-bar button:hover:not(#tasklist-button),
+  panel-toplevel.background button:hover:not(#tasklist-button), .xfce4-panel.panel button.flat:hover, .xfce4-panel.panel button.sidebar-button:hover {
     border: none;
     background-color: #414654; }
   .gnome-panel-menu-bar button:active:not(#tasklist-button),
-  .mate-panel-menu-bar button:active:not(#tasklist-button), .xfce4-panel.panel button.flat:active, .xfce4-panel.panel button.sidebar-button:active, .gnome-panel-menu-bar button:checked:not(#tasklist-button),
-  .mate-panel-menu-bar button:checked:not(#tasklist-button), .xfce4-panel.panel button.flat:checked, .xfce4-panel.panel button.sidebar-button:checked {
+  .mate-panel-menu-bar button:active:not(#tasklist-button),
+  panel-toplevel.background button:active:not(#tasklist-button), .xfce4-panel.panel button.flat:active, .xfce4-panel.panel button.sidebar-button:active, .gnome-panel-menu-bar button:checked:not(#tasklist-button),
+  .mate-panel-menu-bar button:checked:not(#tasklist-button),
+  panel-toplevel.background button:checked:not(#tasklist-button), .xfce4-panel.panel button.flat:checked, .xfce4-panel.panel button.sidebar-button:checked {
     color: #ffffff;
     border: none;
     background-color: #5294e2; }
diff --git a/common/gtk-3.0/3.20/gtk-solid.css b/common/gtk-3.0/3.20/gtk-solid.css
index 2fa9cfe..5792d76 100644
--- a/common/gtk-3.0/3.20/gtk-solid.css
+++ b/common/gtk-3.0/3.20/gtk-solid.css
@@ -3315,7 +3315,9 @@ button.documents-favorite:active:hover {
 
 .gnome-panel-menu-bar, .gnome-panel-menu-bar menubar,
 .mate-panel-menu-bar,
-.mate-panel-menu-bar menubar {
+.mate-panel-menu-bar menubar,
+panel-toplevel.background,
+panel-toplevel.background menubar {
   background-color: #2b2e37; }
 
 .gnome-panel-menu-bar menubar,
@@ -3323,7 +3325,10 @@ button.documents-favorite:active:hover {
 .gnome-panel-menu-bar #PanelApplet image,
 .mate-panel-menu-bar menubar,
 .mate-panel-menu-bar #PanelApplet label,
-.mate-panel-menu-bar #PanelApplet image {
+.mate-panel-menu-bar #PanelApplet image,
+panel-toplevel.background menubar,
+panel-toplevel.background #PanelApplet label,
+panel-toplevel.background #PanelApplet image {
   color: #BAC3CF; }
 
 .gnome-panel-menu-bar button label, .gnome-panel-menu-bar button image,
@@ -3332,23 +3337,31 @@ button.documents-favorite:active:hover {
 .mate-panel-menu-bar button label,
 .mate-panel-menu-bar button image,
 .mate-panel-menu-bar #tasklist-button label,
-.mate-panel-menu-bar #tasklist-button image {
+.mate-panel-menu-bar #tasklist-button image,
+panel-toplevel.background button label,
+panel-toplevel.background button image,
+panel-toplevel.background #tasklist-button label,
+panel-toplevel.background #tasklist-button image {
   color: inherit; }
 
 .gnome-panel-menu-bar .wnck-pager,
-.mate-panel-menu-bar .wnck-pager {
+.mate-panel-menu-bar .wnck-pager,
+panel-toplevel.background .wnck-pager {
   color: #5d6268;
   background-color: #14161b; }
   .gnome-panel-menu-bar .wnck-pager:hover,
-  .mate-panel-menu-bar .wnck-pager:hover {
+  .mate-panel-menu-bar .wnck-pager:hover,
+  panel-toplevel.background .wnck-pager:hover {
     background-color: #363a46; }
   .gnome-panel-menu-bar .wnck-pager:selected,
-  .mate-panel-menu-bar .wnck-pager:selected {
+  .mate-panel-menu-bar .wnck-pager:selected,
+  panel-toplevel.background .wnck-pager:selected {
     color: #a9caf1;
     background-color: #5294e2; }
 
 .gnome-panel-menu-bar na-tray-applet,
-.mate-panel-menu-bar na-tray-applet {
+.mate-panel-menu-bar na-tray-applet,
+panel-toplevel.background na-tray-applet {
   -NaTrayApplet-icon-padding: 0;
   -NaTrayApplet-icon-size: 16px; }
 
@@ -3371,18 +3384,22 @@ button.documents-favorite:active:hover {
     box-shadow: inset 0 -2px #5294e2; }
 
 .gnome-panel-menu-bar button:not(#tasklist-button),
-.mate-panel-menu-bar button:not(#tasklist-button), .xfce4-panel.panel button.flat, .xfce4-panel.panel button.sidebar-button {
+.mate-panel-menu-bar button:not(#tasklist-button),
+panel-toplevel.background button:not(#tasklist-button), .xfce4-panel.panel button.flat, .xfce4-panel.panel button.sidebar-button {
   color: #BAC3CF;
   border-radius: 0;
   border: none;
   background-color: rgba(43, 46, 55, 0); }
   .gnome-panel-menu-bar button:hover:not(#tasklist-button),
-  .mate-panel-menu-bar button:hover:not(#tasklist-button), .xfce4-panel.panel button.flat:hover, .xfce4-panel.panel button.sidebar-button:hover {
+  .mate-panel-menu-bar button:hover:not(#tasklist-button),
+  panel-toplevel.background button:hover:not(#tasklist-button), .xfce4-panel.panel button.flat:hover, .xfce4-panel.panel button.sidebar-button:hover {
     border: none;
     background-color: #414654; }
   .gnome-panel-menu-bar button:active:not(#tasklist-button),
-  .mate-panel-menu-bar button:active:not(#tasklist-button), .xfce4-panel.panel button.flat:active, .xfce4-panel.panel button.sidebar-button:active, .gnome-panel-menu-bar button:checked:not(#tasklist-button),
-  .mate-panel-menu-bar button:checked:not(#tasklist-button), .xfce4-panel.panel button.flat:checked, .xfce4-panel.panel button.sidebar-button:checked {
+  .mate-panel-menu-bar button:active:not(#tasklist-button),
+  panel-toplevel.background button:active:not(#tasklist-button), .xfce4-panel.panel button.flat:active, .xfce4-panel.panel button.sidebar-button:active, .gnome-panel-menu-bar button:checked:not(#tasklist-button),
+  .mate-panel-menu-bar button:checked:not(#tasklist-button),
+  panel-toplevel.background button:checked:not(#tasklist-button), .xfce4-panel.panel button.flat:checked, .xfce4-panel.panel button.sidebar-button:checked {
     color: #ffffff;
     border: none;
     background-color: #5294e2; }
diff --git a/common/gtk-3.0/3.20/gtk.css b/common/gtk-3.0/3.20/gtk.css
index 7d54389..962d5a2 100644
--- a/common/gtk-3.0/3.20/gtk.css
+++ b/common/gtk-3.0/3.20/gtk.css
@@ -3315,7 +3315,9 @@ button.documents-favorite:active:hover {
 
 .gnome-panel-menu-bar, .gnome-panel-menu-bar menubar,
 .mate-panel-menu-bar,
-.mate-panel-menu-bar menubar {
+.mate-panel-menu-bar menubar,
+panel-toplevel.background,
+panel-toplevel.background menubar {
   background-color: rgba(43, 46, 55, 0.95); }
 
 .gnome-panel-menu-bar menubar,
@@ -3323,7 +3325,10 @@ button.documents-favorite:active:hover {
 .gnome-panel-menu-bar #PanelApplet image,
 .mate-panel-menu-bar menubar,
 .mate-panel-menu-bar #PanelApplet label,
-.mate-panel-menu-bar #PanelApplet image {
+.mate-panel-menu-bar #PanelApplet image,
+panel-toplevel.background menubar,
+panel-toplevel.background #PanelApplet label,
+panel-toplevel.background #PanelApplet image {
   color: #BAC3CF; }
 
 .gnome-panel-menu-bar button label, .gnome-panel-menu-bar button image,
@@ -3332,23 +3337,31 @@ button.documents-favorite:active:hover {
 .mate-panel-menu-bar button label,
 .mate-panel-menu-bar button image,
 .mate-panel-menu-bar #tasklist-button label,
-.mate-panel-menu-bar #tasklist-button image {
+.mate-panel-menu-bar #tasklist-button image,
+panel-toplevel.background button label,
+panel-toplevel.background button image,
+panel-toplevel.background #tasklist-button label,
+panel-toplevel.background #tasklist-button image {
   color: inherit; }
 
 .gnome-panel-menu-bar .wnck-pager,
-.mate-panel-menu-bar .wnck-pager {
+.mate-panel-menu-bar .wnck-pager,
+panel-toplevel.background .wnck-pager {
   color: #5d6268;
   background-color: rgba(20, 22, 27, 0.95); }
   .gnome-panel-menu-bar .wnck-pager:hover,
-  .mate-panel-menu-bar .wnck-pager:hover {
+  .mate-panel-menu-bar .wnck-pager:hover,
+  panel-toplevel.background .wnck-pager:hover {
     background-color: rgba(54, 58, 70, 0.95); }
   .gnome-panel-menu-bar .wnck-pager:selected,
-  .mate-panel-menu-bar .wnck-pager:selected {
+  .mate-panel-menu-bar .wnck-pager:selected,
+  panel-toplevel.background .wnck-pager:selected {
     color: #a9caf1;
     background-color: #5294e2; }
 
 .gnome-panel-menu-bar na-tray-applet,
-.mate-panel-menu-bar na-tray-applet {
+.mate-panel-menu-bar na-tray-applet,
+panel-toplevel.background na-tray-applet {
   -NaTrayApplet-icon-padding: 0;
   -NaTrayApplet-icon-size: 16px; }
 
@@ -3371,18 +3384,22 @@ button.documents-favorite:active:hover {
     box-shadow: inset 0 -2px #5294e2; }
 
 .gnome-panel-menu-bar button:not(#tasklist-button),
-.mate-panel-menu-bar button:not(#tasklist-button), .xfce4-panel.panel button.flat, .xfce4-panel.panel button.sidebar-button {
+.mate-panel-menu-bar button:not(#tasklist-button),
+panel-toplevel.background button:not(#tasklist-button), .xfce4-panel.panel button.flat, .xfce4-panel.panel button.sidebar-button {
   color: #BAC3CF;
   border-radius: 0;
   border: none;
   background-color: rgba(43, 46, 55, 0); }
   .gnome-panel-menu-bar button:hover:not(#tasklist-button),
-  .mate-panel-menu-bar button:hover:not(#tasklist-button), .xfce4-panel.panel button.flat:hover, .xfce4-panel.panel button.sidebar-button:hover {
+  .mate-panel-menu-bar button:hover:not(#tasklist-button),
+  panel-toplevel.background button:hover:not(#tasklist-button), .xfce4-panel.panel button.flat:hover, .xfce4-panel.panel button.sidebar-button:hover {
     border: none;
     background-color: rgba(65, 70, 84, 0.95); }
   .gnome-panel-menu-bar button:active:not(#tasklist-button),
-  .mate-panel-menu-bar button:active:not(#tasklist-button), .xfce4-panel.panel button.flat:active, .xfce4-panel.panel button.sidebar-button:active, .gnome-panel-menu-bar button:checked:not(#tasklist-button),
-  .mate-panel-menu-bar button:checked:not(#tasklist-button), .xfce4-panel.panel button.flat:checked, .xfce4-panel.panel button.sidebar-button:checked {
+  .mate-panel-menu-bar button:active:not(#tasklist-button),
+  panel-toplevel.background button:active:not(#tasklist-button), .xfce4-panel.panel button.flat:active, .xfce4-panel.panel button.sidebar-button:active, .gnome-panel-menu-bar button:checked:not(#tasklist-button),
+  .mate-panel-menu-bar button:checked:not(#tasklist-button),
+  panel-toplevel.background button:checked:not(#tasklist-button), .xfce4-panel.panel button.flat:checked, .xfce4-panel.panel button.sidebar-button:checked {
     color: #ffffff;
     border: none;
     background-color: #5294e2; }
diff --git a/common/gtk-3.0/3.20/sass/_applications.scss b/common/gtk-3.0/3.20/sass/_applications.scss
index c6cb1dd..6b9d8df 100644
--- a/common/gtk-3.0/3.20/sass/_applications.scss
+++ b/common/gtk-3.0/3.20/sass/_applications.scss
@@ -434,7 +434,8 @@ button.documents-favorite:active:hover {
 // Mate/Gnome Flashback Panel
 //
 .gnome-panel-menu-bar,
-.mate-panel-menu-bar {
+.mate-panel-menu-bar,
+panel-toplevel.background {
 
   &, menubar { background-color: $panel_bg; }