.wrapper {
 
  height: 200px;
  background:#99ff66;
  border-top: none;
  position: relative;
  overflow: hidden;
  z-index: 1;
}

.wrapper:before {
  content: '';
  position: absolute;
  width: 100%;
  height: 100%;
  border-radius: 80%;
  
  background:white;
  left: 0;
  top: -50%;
  z-index: 2;

}
a:hover{
  cursor: pointer;
}