Why does a2ui-root use max-height: 80% on :host?

[Prithviraj-debug]

In the Lit renderer, a2ui-root defines the following :host styles in renderers/lit/src/0.8/ui/root.ts:

:host {
  display: flex;
  flex-direction: column;
  gap: 8px;
  max-height: 80%;
}

Could someone clarify the design rationale for max-height: 80% in particular?

Understanding whether this is meant for chat-style layouts (e.g. reserving space for an input area or header), for scroll behavior, or for something.

Thanks.