<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1"> <title>ACE Editor Inside iframe</title> <style type="text/css" media="screen"> /*!important without this top: 0; bottom: 0 doesn't work */ body, html { position: absolute; top: 0px; bottom: 0; left: 0; right: 0; margin:0; padding:0; overflow:hidden } #editor { padding: 20px; position: absolute; width: 80%; height: 80%; } </style> </head> <body> <iframe id="editor" src="../kitchen-sink.html"></iframe> </body> </html>