div.auction > ul > li:nth-child(4n+1) {  
  background:aliceblue;
}

div.auction > ul > li:nth-child(4n+2) {  
  background:aliceblue;
}

div.auction > ul > li:nth-child(4n) {  
  background:ivory;
}

div.auction > ul > li:nth-child(4n+3) {  
  background:ivory;
}

div.auction > ul > li {
    font-weight: bolder;
}