controlsfx popover style CSS

Question

How can I change, from CSS, the left arrow fill color in popover from JavaFx?

I tried the following, but it didn't work.

   .popover > .content {
    -fx-fill: yellow !important;
    -fx-background-color: red !important; 

}

popover  > .content > .accordion > .titled-pane > .title > .arrow-button > .arrow {
    -fx-background-color: red !important;
    -fx-fill: red !important;
    -fx-pref-height: 34.0 !important;
}

.popover  > .content > .accordion > .titled-pane > .title > .arrow-button {
    -fx-background-color: yellow !important;
    -fx-fill:yellow !important;
}

Answer 1

i solved using .

.popover > .border  {
    -fx-border-style: none;
    -fx-padding: 0;
    -fx-border-width: 0;
    -fx-fill: rgba(255,255,255,0.5);
}

Answer 2

I solved using:

.popover > .border {
    -fx-stroke-width: 0;
    -fx-fill: rgba(255,255,255,1) !important;
    -fx-effect: dropshadow(gaussian, lightgray, 6.0, 0.0, 1.0, 1.0);
}