danieliser/hide-header-footer-in-iframe.css

## hide-header-footer-in-iframe.css
html.loaded-in-iframe #header,
html.loaded-in-iframe #footer,
html.loaded-in-iframe #wpadminbar {
  display: none!important;
}

## hide-header-footer-in-iframe.js
function inIframe() {
  try {
    return window.self !== window.top;
  } catch (Exception) {
    return true;
  }
}

if (inIframe()) {
  document.getElementsByTagName('html')[0].classList.add('loaded-in-iframe');
  // Alternatively you could skip the CSS and just hide elements using JavaScript here!.
}