h1 {
  text-align: center; 
  background-color: white
}
section{
  width: 800px ;
  height: 300px ;
  background-color: lightgrey;
  margin: 0rem auto;
}

div{
  width: 20px;
  height: 20px;
  background-color: green;
  position: relative;
  top: 0;
  bottom: 0;

}