Q:

JavaFX how to style the button part of a checkbox? 

I am trying to do some css styling in a stylesheet for a JavaFX scene. 
It is going to be loaded upon opening the scene, and targets all the "basic" elements of a scene. 
My problem is that i can't seem to find the right combination of code, to change the background color, of the button in a standard JavaFX checkbox. 
This is where i am now:
.check-box:selected{
    -fx-background-color: #00FF00;
}

I have tried some variants of the above, like 
.check-box .button{
    -fx-fill: #00FF00;
    -fx-background-color: #00FF00;
}

and others, but without success. 
So in general, how do i access a button in a checkbox? 
Thank you in advance :-)

A:

The parts of the CheckBox to apply the -fx-background-color to are .box and .box > .mark in case you want to change the mark color:
.check-box:selected > .box {
    /* background color for selected checkbox */
    -fx-background-color: lime;
}

.check-box > .box {
    /* background color of unselected checkbox */
    -fx-background-color: red;
}

.check-box:selected > .box > .mark,
.check-box:indeterminate  > .box > .mark {
    /* modify mark color */
    -fx-background-color: blue;
}

