For anyone else who might encounter issues using this method, just wanted to add some info:
The CSS works great, but only *if* you haven’t manually set your newsletter form action (using YMLP here, and the API just doesn’t work, as reported by several users before). Once you do that, the plugin will assume you want to use static data (even if not necessary, and even if all fields are blank), and the code in frontend/NewsletterSignUp.php will insert a hidden <div> between the input and signup paragraphs to store that static data. This prevents the inline-block from working properly, so since I wasn’t using static data I just commented out that if-statement in the php file. Lines up nicely now.
