* {
  margin: 0px;
  padding: 0px;
  box-sizing: border-box;
  font-family: sans-serif;
}
.formation {
  width: 55%;
}
@media screen and (max-width: 650px) {
  .formation {
    width: 70%;
  }
}
@media screen and (max-width: 350px) {
  .formation {
    width: 100%;
  }
}