Apple has a private CSS property to add Liquid Glass effects to web content
Apple has developed a private CSS property called `-apple-visual-effect` that enables Liquid Glass effects in web content within iOS apps. The property supports various system materials including the new glass effects from iOS 26, but requires enabling a private WKPreferences setting called `useSystemAppearance`. While this feature can't be used in App Store apps due to its private nature, it suggests Apple is using webviews with native UI integration in their own applications without users realizing it.