Add margin to top of rofi

When run on a display with the waybar at the top, it would obscure the
input bar.

rofi/sidebar.rasi

@@ -54,6 +54,7 @@ window {
 }
 
 mainbox {
+	margin:                      25 0 0 0;
 	spacing:  0.8em;
 	children: [ entry,listview,sidebar ];
 }