import { Attachment, Button, Provider, teamsTheme } from '@fluentui/react-northstar'; import * as React from 'react'; import * as ReactDOM from 'react-dom'; type PortalFrameProps = { children: (externalDocument: Document) => React.ReactElement; }; const PortalFrame: React.FunctionComponent = ({ children }) => { const frameRef = React.useRef(null); const [mounted, setMounted] = React.useState(false); React.useEffect(() => { setMounted(true); }, []); return ( <>