/**
 * Keeps the full-screen panel inside the part of the screen the reader can
 * actually see.
 *
 * On a phone the panel is `position: fixed` across the whole viewport, and
 * that viewport is not what is on screen once a keyboard slides up: the
 * layout viewport keeps its full height, so the composer — and with it the
 * last few messages — ends up behind the keyboard. iOS then scrolls the page
 * to chase the focused field, which moves the fixed panel out of frame
 * instead of helping. `dvh` is no use here either; it tracks the browser's
 * own chrome collapsing, not the keyboard.
 *
 * `visualViewport` is the one thing that does report the visible box, so the
 * panel is pinned to it: its top to `offsetTop`, its height to `height`. The
 * composer lands just above the keyboard, and the conversation gets whatever
 * is left.
 *
 * A pinch is left alone. Zooming is how a reader gets a closer look, and a
 * panel that re-fitted itself to the magnified box would take that away by
 * reflowing the text back to the same apparent size.
 *
 * @implements {ReactiveController}
 */
export class ViewportController implements ReactiveController {
    /**
     * @param {LitElement} host
     * @param {{ enabled: () => boolean }} options
     */
    constructor(host: LitElement, { enabled }: {
        enabled: () => boolean;
    });
    hostConnected(): void;
    hostDisconnected(): void;
    hostUpdated(): void;
    #private;
}
import type { ReactiveController } from 'lit';
import type { LitElement } from 'lit';