Form fields are extremely wide

Open up the CSS file in an editor and then un-minimize it — it’s minimized, which makes it very hard to search. Then look for the part Jasbir is talking about.

You may not be able to make additions to that same CSS file, of course. But that’s OK, because you can add your own CSS file with style overrides to Marketo Design Studio, then reference that file in your page. This is the best way to manage form-specific styles.