<!doctype html> <html> <head> <meta charset="utf-8" /> <style> html, body { height: 100%; } #outside { display: block; height: 15%; width: 100%; } #embed { height: 70%; width: 100%; } </style> </head> <body> <h3>Embed Grist</h3> <textarea id='outside'></textarea> <iframe id='embed' src=""></iframe> </body> </html>