FXML:
<StackPane fx:id="root" xmlns="http://javafx.com/javafx" xmlns:fx="http://javafx.com/fxml">
    <Line endX="${root.width}" endY="${root.height}" styleClass="blue"/>
    <Line endX="${root.width}" startY="${root.height}" styleClass="blue"/>
    <Label text="This is a label with a border" styleClass="red"/>
</StackPane>

CSS:
#root {
    -fx-padding: 25px;
    -fx-background-color: white;
}
.red {
    -fx-padding: 50px;
    -fx-background-color: rgba(255, 255, 255, 0.9);
    -fx-background-radius: 50px;
    -fx-border-style: segments(5px, 15px, 0px, 15px) line-cap square;
    -fx-border-width: 5px;
    -fx-border-radius: 50px;
    -fx-border-color: crimson;
}
.blue {
    -fx-stroke: dodgerblue;
    -fx-stroke-width: 5px;
    -fx-stroke-line-cap: square;
    -fx-stroke-dash-array: 25px 15px 0px 15px;
}