Andy, in your example, it looks like you're not loading the default form styles, that's why the calendar is all wonky.
Are you using the shortcode to add the form into a post, or using the function call to embed it into the page template?
If you're using the shortcode, make sure you have the "output css" option in the form settings set to yes. If you've disabled that on purpose, you can go the forms.css in the plugin folder and copy the block for the calendar styles and add those to your theme style sheet.
If you are using the function call, you need to manually enqueue the scripts/css by adding short code snippet to your functions.php file. You can find that at the bottom of the page here.
Let us know how it goes.
Posted 9 years ago on Thursday July 8, 2010 | Permalink