Inserted form breaks width of webpage layout

Hello!

I am currently using Fast Secure Contact Form plugin that allows for attachment files to be sent along with the form information, but it somehow conflicts with the width space of my webpage layout.

Placing the form through using the shortcode on the following webpage makes the width of the webpage go from full page width to something like 600 pixels.

How can I control the width of the inserted form?

Changing the “CSS style for form DIV”-value to “width:100%;” (width:300px; is default value) under the “Style form” options doesn’t seem to help with solving this issue.

Here’s a link to the website: http://www.froso.dk/wordpress/omfroso/ledige-stillinger/

Any suggestions to fix this?

Thank you!

http://wordpress.org/extend/plugins/si-contact-form/