Latest update removed custom css button (please help?)

Here’s the css I’ve been using to display a .png submit image for the Jetpack subscriptions widget:

#subscribe-submit input {
	background: url(images/go.png) no-repeat 0 0 !important;
	border: none;
	height: 30px;
	left: 2px;
	position: relative;
	width: 47px !important;
}

What can I do to fix?