[overview] Port pane to CSS

https://bugzilla.gnome.org/show_bug.cgi?id=600734

data/Makefile.am

@@ -16,7 +16,6 @@ imagesdir = $(pkgdatadir)/images
 dist_images_DATA =				\
 	add-workspace.svg			\
 	app-well-glow.png			\
-	close.svg				\
 	close-black.svg				\
 	info.svg				\
 	magnifier.svg				\
@@ -25,6 +24,7 @@ dist_images_DATA =				\
 themedir = $(pkgdatadir)/theme
 dist_theme_DATA =				\
 	theme/gnome-shell.css			\
+	theme/close.svg                 \
 	theme/scroll-button-down.png		\
 	theme/scroll-button-down-hover.png	\
 	theme/scroll-button-up.png		\

data/theme/gnome-shell.css

@@ -137,6 +137,19 @@ StTooltip {
     font-weight: normal;
 }
 
+.dash-pane {
+    background-color: rgba(0,0,0,0.95);
+    border: 1px solid #262626;
+    padding: 4px;
+    spacing: 4px;
+}
+
+.dash-pane-close {
+    background-image: url("close.svg");
+    width: 16px;
+    height: 16px;
+}
+
 /* LookingGlass */
 
 #LookingGlassDialog