How do I style Campaign Monitor forms (added via the code block)?

I would like to add a Campaign Monitor form to a Squarespace page. Everything works fine in terms of the functionality of the form, but it winds up reverting to default formatting and doesn't inherit the CSS styles from the Squarespace template.

Is there a way to get custom forms created using the code block to inherit the form and button styles of the theme?

Here's a quick guide to how things work on the Campaign Monitor side: http://help.campaignmonitor.com/topic.aspx?t=13

James