Hi,
First, regarding the buttons, you have two choices:
1. You decide to use the HikaShop button style and thus you remove the CSS of the buttons in your template.
So you would have to remove the code:
input.button, button.button, button.validate {
background: #FFFFFF url(../images/nature/arrow1.gif) no-repeat left top;
border: 1px solid #DDDDDD;
color: #444444;
}
in
www.it-xservice.de/joomla2/templates/beez_20/css/personal.css
or you decide to use your template's buttons and thus you remove the CSS of the buttons in the style file.
Regarding the popup buttons not being displayed, that's just because the message is on two lines in German while it's on one line in most of the other languages. Because of that, the buttons of the popup get a bit pushed down and you don't see them without scrolling. So the simple solution will be to change the text:
www.hikashop.com/download/languages.html#modify
Regarding the products listing in the cart, I don't see the blue header background on your website like you had in a previous screenshot.