But this seems to be generates beneath the <div id="openfl-content"/> - since the div’s default style is 100% width/height, it pushed down the iframe from viewing area of browser.
When you create an iframe dynamically using JavaScript and append it directly to document.body, it might not appear where you intend if there are conflicting CSS styles affecting its position. This can happen if the default styles of a container (openfl-content in your case) force it out of view.