allow any div to be turned into a toplevel.

src/Web/Avalonia.Web.Sample/Avalonia.Web.Sample.csproj

@@ -7,10 +7,17 @@
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <MSBuildEnableWorkloadResolver>true</MSBuildEnableWorkloadResolver>
     <WasmBuildNative>true</WasmBuildNative>
-    <EmccFlags>-sVERBOSE</EmccFlags>
+    <EmccFlags>-sVERBOSE -sERROR_ON_UNDEFINED_SYMBOLS=0</EmccFlags>
     <EmccExtraLDFlags>--js-library="C:\Users\User\repos\Avalonia\src\Web\Avalonia.Web.Sample\interop.js"</EmccExtraLDFlags>
   </PropertyGroup>
 
+  <PropertyGroup Condition="'$(Configuration)'=='Release'">
+    <RunAOTCompilation>true</RunAOTCompilation>
+    <PublishTrimmed>true</PublishTrimmed>
+    <EmccCompileOptimizationFlag>-O3</EmccCompileOptimizationFlag>
+    <EmccLinkOptimizationFlag>-O3</EmccLinkOptimizationFlag>
+  </PropertyGroup>
+
   <ItemGroup>
     <ProjectReference Include="..\..\..\samples\ControlCatalog\ControlCatalog.csproj" />
     <ProjectReference Include="..\Avalonia.Web\Avalonia.Web.csproj" />

src/Web/Avalonia.Web.Sample/Program.cs

@@ -18,7 +18,7 @@ internal partial class Program
 
     private static void Main(string[] args)
     {
-        BuildAvaloniaApp().UseBrowserWasm();
+        BuildAvaloniaApp().SetupBrowserApp("out1");
     }
 
     public static AppBuilder BuildAvaloniaApp()

src/Web/Avalonia.Web/AvaloniaRuntime.cs

@@ -35,7 +35,7 @@ public partial class AvaloniaRuntime
     {
         InterceptGLObject();
 
-        var info = InitGL(canvas, "testCanvas", renderFrameCallback);
+        var info = InitGL(canvas, canvas.GetPropertyAsString("id")!, renderFrameCallback);
 
 
         var glInfo = new GLInfo(

src/Web/Avalonia.Web/AvaloniaView.cs

@@ -47,13 +47,14 @@ namespace Avalonia.Web
 
         private bool _useGL;
         private bool _inputElementFocused;
+        private static int _canvasCount;
 
-        public AvaloniaView()
+        public AvaloniaView(string divId)
         {
-            var div = GetElementById("out");
+            var div = GetElementById(divId);
 
             _canvas = CreateCanvas(div);
-            _canvas.SetProperty("id", "mycanvas");
+            _canvas.SetProperty("id", $"avaloniaCanvas{_canvasCount++}");
 
             _topLevelImpl = new RazorViewTopLevelImpl(this);
 

src/Web/Avalonia.Web/BlazorSingleViewLifetime.cs

@@ -19,13 +19,10 @@ namespace Avalonia.Web.Blazor
 
     public static partial class WebAppBuilder
     {
-        
-
-        public static T UseBrowserWasm<T>(
-        this T builder)
+        public static T SetupBrowserApp<T>(
+        this T builder, string mainDivId)
         where T : AppBuilderBase<T>, new()
         {
-            Console.WriteLine("In UseBrowserWasm");
             var lifetime = new BlazorSingleViewLifetime();
 
             return builder
@@ -34,13 +31,9 @@ namespace Avalonia.Web.Blazor
                 .With(new SkiaOptions { CustomGpuFactory = () => new BlazorSkiaGpu() })
                 .AfterSetup(b =>
                 {
-                    var view = new AvaloniaView();
-                    lifetime.View = view;
-                    Console.WriteLine("After setup");
-
+                    lifetime.View = new AvaloniaView(mainDivId);
                 })
                 .SetupWithLifetime(lifetime);
-
         }
     }
 }