Add support for dynamic CSS #61

Sources/Adwaita/AnyView++.swift

@@ -339,11 +339,15 @@ extension AnyView {
     /// - Parameter getString: Get the CSS.
     /// - Returns: A view.
     public func css(_ getString: @escaping () -> String) -> AnyView {
-        inspectOnAppear { _ in
+        inspect { storage, updateProperties in
+            let cssID = "internal-css"
+            let previous = storage.fields[cssID] as? String
+            let string = getString()
+            if updateProperties, string != previous {
                 let provider = gtk_css_provider_new()
                 gtk_css_provider_load_from_string(
                     provider,
-                getString()
+                    string
                 )
                 let display = gdk_display_get_default()
                 gtk_style_context_add_provider_for_display(
@@ -354,5 +358,6 @@ extension AnyView {
                 g_object_unref(provider)
             }
         }
+    }
 
 }

Sources/Demo/DiceDemo.swift

@@ -32,7 +32,8 @@ struct DiceDemo: View {
             .css {
                 """
                 .dice-button {
-                    background-color: @green_5;
+                    background-color: \(number == nil ? "@blue_5" : "@green_5");
+                    transition: 0.2s;
                 }
                 """
             }