<!DOCTYPE html> <html> <body> <h1>The iframe sandbox attribute</h1> <iframe src="https://horje.com" sandbox="allow-forms"> <p>Your browser does not support iframes.</p> </iframe> <p>The "Submit" button will submit the form in the inline frame.</p> <p>Since the sandbox attribute is set to an empty string (""), the submission of the form in the inline frame will be blocked.</p> <p>Add "allow-forms" to the sandbox attribute, to allow form submission.</p> </body> </html>