Here is a sample which displays a scroll bar with a transparent background.
The sample includes some extra program logic to only show visual feedback on the scrollbar when the user hovers over the scrollbar - you may or may not need that.
The css related to the scrollbar in the sample is:
.address .scroll-pane {
-fx-background-color: transparent;
}
.address .scroll-bar .increment-button {
visibility: hidden;
}
.address .scroll-bar .decrement-button {
visibility: hidden;
}
.address .scroll-bar:vertical {
-fx-background-color: transparent;
}
.address .scroll-bar:vertical .track-background {
visibility: hidden;
}
.address .scroll-bar:vertical .track {
visibility: hidden;
}
.address .hide-thumb .scroll-bar:vertical .thumb {
-fx-background-color: transparent;
}
Where the scroll bar being made transparent has the additional custom style class of address assigned to it.
I determined the css to use by studying the scroll-bar section of the default JavaFX 2.2 css stylesheet caspian.css.
Output of the sample is: