DocSpace-buildtools/web/ASC.Web.Editor/pages/_app.js

import { createGlobalStyle } from "styled-components";

const GlobalStyle = createGlobalStyle`
body {
    margin: 0;
}

html, body {
    height: 100%;
}
`;

export default function App({ Component, pageProps }) {
  return (
    <>
      <GlobalStyle />
      <Component {...pageProps} />
    </>
  );
}