Woocommerce cart and checkout page breaking issue

Hello iam having a problem with Woocommerce cart and checkout page breaking.
You can see below on the printscreens how it looks like:

Cart
Checkout
Checkout1
Iam using the themeforest->SimpleKey theme which is compatible with Woocommerce plugin.
I have checked many forums for the same problem,but could’t get any solution
to it. I also added WP_DEBUG to the top of wp-config.php in order to check for any problems but it didnt show any error or warning.
Can anyone help and propose some solution if you have encountered this kind of issue.
My website url is unidast.gr