After you specify the data source and event dates, configure how the Timeline control is visually displayed. You can specify the height of the control and a stylesheet for the control.
In the Height (px) field on the Presentation tab of the Properties panel, specify the height in pixels for the Timeline control.
Optional: To override the application's default style sheet, enter a class name in the Custom CSS class field. For example, your application's style sheet can define styles for different kinds of timelines, depending on what type of event is being displayed. You would enter the appropriate value that overrides .vis-timeline . For more information on timeline styles, see the Vis.js website.
Click Submit.