.classA {
  border-color: white;
  border-top: 13px;
  border: 1px;
  border-style: solid;
  vertical-align: top;
}
.classB {
  background-color: red;
  border-color: #FF0000;
  border-top: 13px;
  border: 1px;
  border-style: solid;
  vertical-align: top;
  
}