Slider dimensions

Hello,

firstly I would like to say a big thank you, as the theme is very easy to control, even for those that don’t have big experience with wordpress.
Secondly, I would like to ask you if there is a way not to change the slider dimensions when the browser dimensions change as it sometimes causes the images to awfully stretch. [http://desapone.gr/]
Thank you in advance for your time.

cheers,
maro