Hi, can someone help me achieve what Washington DC Classifieds - Free Classifieds Ads for Washington DC, District of Columbia, Virginia, Maryland at eBay Classifieds (Kijiji). does when you highlight a category. They have a stroke around the background-color. What is the syntax to do this with CSS?

Code:
a:hover{background-color:#003366;color:#fff;text-decoration:none;}
Thank you!