UIToolkit UIElements, how to access the hover uss style from code?

Hi, I want to do UIToolkit editor window from pure code without USS/Style sheets/UXML/other wierd things. I simply prefer code.

How do I access in Code the uss hover property

.quicktool-button-icon:hover {
opacity: 1;

I can’t find these psudo classes, in code.

any help appreciated

I have found a way to do it, 1 hour after posting the question

    Button button = new Button();
    button.RegisterCallback<MouseOverEvent>((type) =>
        buttonIcon.style.opacity = 1f;

    button.RegisterCallback<MouseOutEvent>((type) =>
        buttonIcon.style.opacity = 0.5f;