code: private void addMetaTags(UIViewRoot root, FacesContext context) {
  		// Check context-param
  		String viewportParam = BsfUtils.getInitParam(C.P_VIEWPORT, context);
  
  		viewportParam = evalELIfPossible(viewportParam);
  		String content = "width=device-width, initial-scale=1";
  		if (!viewportParam.isEmpty() && isFalseOrNo(viewportParam))
  			return;
  		if (!viewportParam.isEmpty() && !isTrueOrYes(viewportParam))
  			content = viewportParam;
  
  		// Otherwise
  		String viewportMeta = "<meta name=\"viewport\" content=\"" + content + "\"/>";
  		UIOutput viewport = new UIOutput();
  		viewport.setRendererType("javax.faces.Text");
  		viewport.getAttributes().put("escape", false);
  		viewport.setValue(viewportMeta);
  
  		UIComponent header = findHeader(root);
  		if (header != null) {
  			header.getChildren().add(0, viewport);
  		}
  	}
docs: Add the viewport meta tag if not disabled from context-param
  
  @param root
  @param context
  @param isProduction