How to give a webview's background a transparent blur effect?

3D WebView doesn't have a built-in way to give a webview's background a transparent blur effect (like frosted glass), but here is a suggested approach for achieving that:

1. Place a CanvasWebViewPrefab in a Canvas and set its URL to load your web page.
2. Enable a transparent background for your web page.
3. Place a RawImage in the Canvas behind the CanvasWebViewPrefab to serve as its background.
4. Use the approaches described in this Stack Overflow answer or this Unity forum thread to add a blur effect to the background RawImage.