Woocommerce Image resize issue

Greetings,

To get right to the point, I used the the css code below to re-size my image and it worked perfectly, however my thumbnail image was also changed and enlarged, which I did not want. Can you please help me as to what I can use to keep my image size as well as the small thumbnail size? Again the code below fixed my single product image but it made my thumbnail image larger,is there a code where I can have my cake and eat to or shall I say keep my product image the same and make my thumbnail small again?

.woocommerce div.product div.images img {
width: auto !important;
}