QWebEngineView: How to change/remove the border color of the drop-down list displayed by <select>?

[deleted312]

I have an application that uses a QWebEngineView to display an HTML page.
When I use a <select> in the HTML content, the drop-down list is displayed with a colored border (yellow on Windows, blue on macOS).
I would like to change this color, or alternatively remove this border.

I can control the QWebEngineView, HTML content and CSS. However I did not find any solution yet.
Is there any way to achieve that?

Steps to reproduce:

• Compile and run the SimpleBrowser example
• Open the url https://www.w3schools.com/tags/tryit.asp?filename=tryhtml_select
• Click on the menu to display the drop-down list

Result: The drop-down list has a 1 pixel colored border. On Windows the color is yellow, on macOS the color is blue.

Thanks!