.slider ul, .slider li {
  margin: 0;
  padding: 0;
  list-style: none;
}

.slider li {
  /* 
    define width and height of list item (slide)
    entire slider area will adjust according to the parameters provided here
  */ 
  width: 648px;
  height: 100px;
  overflow: hidden; 
}

/*
.slider li div {
  width: 640px;
}
*/

span.prevBtn{}
span.nextBtn{}