code: private void addResponsiveExample() {
  		add(new WHeading(HeadingLevel.H2, "Default responsive design"));
  		add(new ExplanatoryText("This example applies the theme's default responsive design rules for ColumnLayout.\n "
  				+ "The columns have width and alignment and there is also a hgap and a vgap."));
  				WPanel panel = new WPanel();
  		panel.setLayout(new ColumnLayout(new int[]{33, 33, 33},
  				new Alignment[]{Alignment.LEFT, Alignment.CENTER, Alignment.RIGHT}, 12, 18));
  		panel.setHtmlClass(HtmlClassProperties.RESPOND);
  		add(panel);
  		panel.add(new BoxComponent("Left"));
  		panel.add(new BoxComponent("Center"));
  		panel.add(new BoxComponent("Right"));
  		panel.add(new BoxComponent("Left"));
  		panel.add(new BoxComponent("Center"));
  		panel.add(new BoxComponent("Right"));
  	}
docs: Add a column layout which will change its rendering on small screens.