* {
  margin: 0; padding: 0;
}
html {
  font-family: sans-serif;
  font-size: 16px;
}
body {
  background: #ccc;
  color: #000;
}
a {
  text-decoration: none;
  color: #00f;
}
header {
  background: #fff;
  width: 80%;
  margin: 1em auto;
  text-align: center;
}

#div_ret_accueil {
  font-size: 14px;
  padding: 5px;
  position: fixed;
  top:5px; right: 10px;
  background: #008;
  color: #fff;
  text-align: center;
  cursor: pointer;
}

@media print {
  #div_ret_accueil {
    display: none;
  }
}