Fix Crowdsignal signup button story

Author: adamwoodnz

client/blocks/signup-form/stories/shared.tsx

@@ -36,9 +36,11 @@ export const BlazeWrapper = ( Story: StoryFn ) => (
 
 export const CrowdsignalWrapper = ( Story: StoryFn ) => (
 	<div className="crowdsignal">
-		<div className="signup-form__crowdsignal" style={ { maxWidth: '360px', padding: '30px' } }>
-			<div className="card logged-out-form__footer">
-				<Story />
+		<div className="signup is-crowdsignal">
+			<div className="signup-form__crowdsignal" style={ { maxWidth: '360px', padding: '30px' } }>
+				<div className="card logged-out-form__footer">
+					<Story />
+				</div>
 			</div>
 		</div>
 	</div>