chatpdf/styles/chrome-bug.css

/**
 * Chrome has a bug with transitions on load since 2012!
 *
 * To prevent a "pop" of content, you have to disable all transitions until
 * the page is done loading.
 *
 * https://lab.laukstein.com/bug/input
 * https://twitter.com/timer150/status/1345217126680899584
 */
body.loading * {
  transition: none !important;
}