Contact Form 7 width

Hi all,
I am very impressed with this nice theme…THANK YOU

I am trying to change the width of a contact form (created using the contact form 7 plugin)but it is impossible..
Below is the structure of the form..

<p>Το ?νομ? σα?*
[text* your-name] </p>

<p>Το επ?θετ? σα?*
[text* your-surname 5/5] </p>

But whatever I do the form width never changes….
I believe it’s a theme issue but I am not sure
Please help..