file.css

.scroll-pane {
    -fx-border-color: black;
    -fx-background-color: rgb(0, 0, 0)
}

.scroll-bar:vertical, .scroll-bar:horizontal {
    -fx-background-color: #000000;
    -fx-background-radius: 5em;
}

.scroll-bar .thumb {
    -fx-background-color: #666;
    -fx-background-insets: 2, 0, 0;
    -fx-background-radius: 5em;
}

.scroll-bar .thumb:hover {
    -fx-background-color: #555;
    -fx-background-radius: 5em;
}

.scroll-bar .increment-button, .scroll-bar .decrement-button {
    -fx-background-color: #333;
    -fx-background-radius: 5em;
}

.scroll-bar:horizontal .increment-button,
.scroll-bar:horizontal .decrement-button {
    -fx-background-radius: 0 5em 5em 0;
}

.scroll-bar:vertical .increment-button,
.scroll-bar:vertical .decrement-button {
    -fx-background-radius: 0 0 5em 5em;
}

.scroll-bar .increment-arrow, .scroll-bar .decrement-arrow {
    -fx-background-color: #999;
}

.scroll-bar:horizontal .increment-arrow {
    -fx-shape: "M 0 0 L 4 2 L 0 4 z";
}

.scroll-bar:vertical .increment-arrow {
    -fx-shape: "M 0 0 L 2 4 L 4 0 z";
}

.scroll-pane > .corner {
    -fx-background-color: black;
}