How can I set the combobox onselected background colour?

[hahadelphi]

from the document, the background is yellow as below

but my project is lightgrey. How can i set the option to change it?

[stworthy]

Please try to override the '.combobox-item-selected' style.

Code:

<style>
  .combobox-item-selected{
    background-color: #ccc;
  }
</style>