FULL PRODUCT VERSION :
java version "9"
Java(TM) SE Runtime Environment (build 9+181)
Java HotSpot(TM) 64-Bit Server VM (build 9+181, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
macOS Sierra, 10.12.6

A DESCRIPTION OF THE PROBLEM :
The layout of table and tree table view column headers becomes messed up when specifying a preferred height for the column headers inside a stylesheet.

REGRESSION. Last worked in version 8u144

ADDITIONAL REGRESSION INFORMATION:
java version "1.8.0_144"
Java(TM) SE Runtime Environment (build 1.8.0_144-b01)
Java HotSpot(TM) 64-Bit Server VM (build 25.144-b01, mixed mode)


STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Run this application. Make sure the stylesheet.css file is in the same location.



EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The five column headers created by the test application should be simply taller than their default height. They should be as tall as the value specified via -fx-pref-height inside the stylesheet.
ACTUAL -
The column headers do have the specified new height but in addition one can see a blank column header above spanning all five columns. It almost looks like a parent column header.

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableView;
import javafx.stage.Stage;

public class TableViewBug extends Application {

    @Override
    public void start(Stage primaryStage) throws Exception {

        TableView<String> tableView = new TableView<>();
        for (int i = 0; i < 5; i++) {
            TableColumn<String, String> column = new TableColumn<>("Col " + i);
            tableView.getColumns().add(column);
        }

        Scene scene = new Scene(tableView);
        scene.getStylesheets().add(TableViewBug.class.getResource("style.css").toExternalForm());

        primaryStage.setScene(scene);
        primaryStage.setWidth(500);
        primaryStage.setHeight(400);
        primaryStage.centerOnScreen();
        primaryStage.show();
    }

    public static void main(String[] args) {
        launch(args);
    }
}

--------------------------- Stylesheet ---------------------------

.column-header {
    -fx-pref-height: 100px;
}
---------- END SOURCE ----------