Problem with form

We have had chronoforms on our site for a couple of years now and never had any problems. Only recently part of the form has disappeared on the page making it impossible for visitor to complete. I've checked the backend and don't see anything obvious, can anyone help?

http://www.sdef.org.uk/index.php/contact-sdef

Hi Sdef2016,

The submit button is being hidden by this CSS in main.css

input {
	 display: none; 
}

Bob