polygerrit-ui/app/styles/gr-a11y-styles.ts

/**
 * @license
 * Copyright 2021 Google LLC
 * SPDX-License-Identifier: Apache-2.0
 */
import {css} from 'lit';

export const a11yStyles = css`
  .assistive-tech-only {
    user-select: none;
    clip: rect(1px, 1px, 1px, 1px);
    height: 1px;
    margin: 0;
    overflow: hidden;
    padding: 0;
    position: absolute;
    white-space: nowrap;
    width: 1px;
    z-index: -1000;
  }
`;

const $_documentContainer = document.createElement('template');
$_documentContainer.innerHTML = `<dom-module id="gr-a11y-styles">
  <template>
    <style>
    ${a11yStyles.cssText}
    </style>
  </template>
</dom-module>`;
document.head.appendChild($_documentContainer.content);