Fix CSS updating on each view update #74

Sources/Adwaita/View/AnyView++.swift

@@ -356,6 +356,7 @@ extension AnyView {
                     .init(GTK_STYLE_PROVIDER_PRIORITY_APPLICATION)
                 )
                 g_object_unref(provider)
+                storage.fields[cssID] = string
             }
         }
     }