After playing with different kinds of Panes I managed to get it to work.
I used a BorderPane and added the child nodes to the left and right of the BorderPane. Now when I re-size the window every element gets re-positioned to its relative position in the starting layout.
Here is the BorderPane part
<BorderPane id="gas-pumps-header" VBox.vgrow="SOMETIMES">
<left>
<Label text="Gas Pumps" BorderPane.alignment="CENTER_LEFT">
<font>
<Font name="System Bold" size="16.0" fx:id="x2" />
</font>
</Label>
</left>
<padding>
<Insets bottom="10.0" left="10.0" right="10.0" top="10.0" fx:id="x3" />
</padding>
<right>
<HBox id="gas-pumps-income-section" alignment="CENTER_RIGHT" spacing="5.0" BorderPane.alignment="CENTER_RIGHT">
<children>
<Label text="Income">
<font>
<Font size="14.0" fx:id="x1" />
</font>
</Label>
<Label fx:id="gasPumpsIncomeValue" font="$x1" text="Value" />
</children>
</HBox>
</right>
</BorderPane>