The label myRightLabel seems to be “floating” because it is misaligned with myLeftLabel. The current difference in font sizes helps improve the situation a little bit, but it’s still noticeable.

<Pane fx:id="myPane" styleClass="my-pane-style">
     <HBox alignment="BOTTOM_LEFT">
         <Label fx:id="myLeftLabel">
             <font><Font name="Tahoma Bold" size="16.0"/></font>
         </Label>
         <Label fx:id="myRightLabel">
              <font>
                  <Font size="15.0" />
              </font>
         </Label>
     </HBox>

In my .css the styling for the pane is defined like so:

.my-pane-style {
-fx-background-color: #ffffff;
background-color: #ffffff;
-fx-opacity: 1;
opacity: 1;
-fx-border-insets: 0 0 0 0;
-fx-border-color: -fx-text-box-border;
-fx-border-width: 2;
}

I’m using the JavaFX that comes with JDK8.