Layouts: Fix styling of "preferences"- and "BackSpace"-buttons

Part-of: <https://gitlab.gnome.org/World/Phosh/squeekboard/-/merge_requests/643>

data/keyboards/es+cat.yaml

@@ -6,7 +6,7 @@ outlines:
     change-view:   { width: 52.67, height: 52 }
     change-view-2:      { width: 62,    height: 52 }
     spaceline: { width: 99.67, height: 52 }
-    special:   { width: 44,    height: 52 }
+    special:   { width: 35.33,    height: 52 }
 
 views:
     base:
@@ -49,7 +49,7 @@ buttons:
         action: "erase"
     preferences:
         action: "show_prefs"
-        outline: "default"
+        outline: "special"
         icon: "keyboard-mode-symbolic"
     show_numbers:
         action: