Webform CSS style.

Hello, i am trying to style a webform. I have managed to do everything apart from changing the submit button hover color.

https://radiantmedia.com.au/newbuild/index.php/252-2/

My current CSS is:

body {
  background-color: #343537;
  font-family: Montserrat;
}
label.webforms__label {
  color: #ec8223;
  font-family: Montserrat;
  font-size: 16px;
}
button[type="submit"] {
  background-color: #ec8223;
}

Thankyou very mcuh