div{
  width: 80%;
  background-color: #777;/*Gris*/
  margin: 20px auto; /*centrée*/
}
p{
  width:100%;
  height:100%;
  background-color: #0CC;/*Bleu-vert*/
  box-sizing:border-box;
  text-align:center;
  line-height: 100px;

}
.bordure{
	border:2px solid black;
}
.arrondi1{
	border-radius:100px/20px;
	
}
.arrondi2{
	border-radius:50px;
	
}
.arrondi3{
	border-radius:25%;
	
}