JavaFX Webview embedded in Swing. How to change scaling?

Question

I use a JavaFX webview inside a Swing application. On my 4k display the content is rendered too small. Fonts are tiny and lines drawn on a canvas are thin (1px). The same content gets rendered properly if I use the JavaFX WebView outside Swing.

Does anyone know, how Swing affects the rendering in JavaFX Webview or if it is possible to set the scaling manually?

Thanks