Hello Vagelis Kretsimos,
The screenshots shows that your alignment problem is not in Sitefinity; Sitefinity just loads your CSS files. As I mentioned in my previous post, you should set some padding of the list.
Here are some links that will help you with CSS:
Also, it will be very useful for you to install FireBug for FireFox that will give you the opportunity to debug your CSS. You can download it from http://www.getfirebug.com/
I hope that this information will be helpful for you.
the Telerik team