Thumbnail image in cart to big

Hi!
The thumbnails images in the main cart is to big. They do not rezise. I read an answear in a topic on this forum that you could add this code in the overide.css
span.cart-images {
display: block;
max-width: 150px;
}
I did that but it does not work if I have set the thumnail size to 600X600px in VM settings and if I set this to 100X100 all images on the site get this sizes and go very unsharp. What am I doing wrong?

Thankful for your help!

Could you please provide me with a URL to your website, either here or via PM (click the “Private Message” text underneath my avatar) so that I may analyze it? It is a lot easier for us to diagnose issues when we have a live site to examine.