ABAshokkumar Balasubramanian Syncfusion Team July 18, 2019 07:50 AM
Hi Ralf Kley,
Greetings from Syncfusion support.
By default our Sidebar component type property value as Auto, so the Sidebar component will be a opened state on desktop and closed state on mobile mode. For your scenario, you can change the type property value as other than Auto (Push, Slide, Over) to achieve your requirement. Please check the below code block.
Note: isOpen property also suitable for this scenario, When the Sidebar type is set to Auto, the component will be expanded in the desktop and collapsed in the mobile mode regardless of the isOpen property.
Could you please check the above provided information and get back to us, if you require any further assistance on this?