TabSheet: This is a basic TabSheet composed using vaadin-tabs and vaadin-tab. The client side of the component is implemented as web component using LitElement, written in TypeScript.
The component has been implemented using Lumo styles and thus should fit fully with other stock Vaadin components.
There is a longer story about how this component was created in this blog post: Create a custom component with Lit | Vaadin
Note, from Vaadin 23.3.0 onwards there is also official version of TabSheet component in the framework. The API of it is a bit different than this add-on version, but the both are roughly similar implementations.