Slider color changes light theme.

JMetroLightTheme.css

/*******************************************************************************
 *                                                                             *
 * Slider                                                                      *
 *                                                                             *
 ******************************************************************************/

/* slider hover */

/* hover for thumb */
.slider:hover .thumb {
    thumb_hover_color: #171717;
}

/* hover for track */
.slider:hover .track {
    -fx-background-color: #666;   
}

/* slider pressed */

/* pressed for thumb */
.slider:pressed .thumb {
    -fx-background-color: #ccc;
}

/* pressed for track */
.slider:pressed .track {
    -fx-background-color: #999;
}

/* slider default background */
.slider .track {
    -fx-background-color: #999;
}