Button CSS differs from version 2 guides?

Hi

Testing version 3. Using this guide: https://docs.mailpoet.com/article/70-design-style-subscription-form-widget-shortcode to make the button in line with the email box on this development site https://marshmill-lancashire.co.uk/ with signup in footer.

Suggested css for styles.css is this:

.widget_wysija .wysija-submit, .widget_wysija .wysija-paragraph { display: inline; }

which has no effect. Using inspect element, it looks like the button dosn’t have the same css class anymore. Anyone know how to fix this issue? Also this needs to go on the docs list for version 3.