Using the class, ".easyazon-block" you can put this code into your CSS styling:
/*comment - easyazon styling*/
.easyazon-block {
background-color: #ffffff;
width: 284px !important;
border-color: #ffbb00 !important;
border-width: 2px !important;
border-radius: 0 !important;
}
The inputs to the background, width and border are examples.