Update xfce4-notifyd specific gtk3 style. Fixes #677.

* Separate #XfceNotifyWindow spesific style

* Move #XfceNotifyWindow code to apps/_xfce.scss

src/gtk-3.0/scss/apps/_xfce.scss

@@ -23,4 +23,17 @@
 
         .menu { -gtk-image-effect: none; }
     }
+
+    #XfceNotifyWindow {
+        background-color: $osd_bg;
+        color: $osd_fg;
+        border-radius: $roundness;
+        border: 1px solid border_normal($osd_bg);
+
+        GtkLabel {
+            &#summary {
+                font-weight: bold;
+            }
+        }
+    }
 }

src/gtk-3.0/scss/widgets/_osd.scss

@@ -8,8 +8,7 @@
 @include exports("osd") {
     GtkOverlay.osd { background-color: transparent; }
 
-    .osd,
-    #XfceNotifyWindow {
+    .osd {
         &.background {
             background-color: alpha($osd_bg, .8);
             color: $osd_fg;

src/gtk-3.20/scss/apps/_xfce.scss

@@ -27,4 +27,21 @@
             text-shadow: none;
         }
     }
+
+    #XfceNotifyWindow {
+        .osd {
+            background-color: $osd_bg;
+            color: $osd_fg;
+            border-radius: $roundness;
+            border: 1px solid border_normal($osd_bg);
+        }
+
+        &.osd {
+            label {
+                &#summary {
+                    font-weight: bold;
+                }
+            }
+        }
+    }
 }

src/gtk-3.20/scss/widgets/_osd.scss

@@ -23,8 +23,7 @@
         }
     }
 
-    button.osd,
-    #XfceNotifyWindow button {
+    button.osd {
         @include button($osd_bg, $osd_fg);
 
         &.image-button {
@@ -73,8 +72,7 @@
         }
     }
 
-    .osd,
-    #XfceNotifyWindow {
+    .osd {
         background-color: $osd_bg;
         color: $osd_fg;