CSS missing using [renewform] shortcode in Membership plugin

I'm using the Membership plugin. I needed to add some additional text to the Subscriptions page, so according to the instructions, I used the shortcode [renewform] with my additional content.

However, the page looks like it now isn't loading the CSS that goes with the form, as my subscription tables are displaying unformatted. I've attached a screenshot.

Has this happened to anyone else?

Did I miss setting an option correctly?