body {
  background-color: #f2f3f1;
  text-align: center;
}

#entete, #menu, #contenu, #footer {
  padding:1px 0;
  }
  #entete {
  background-color:#FF9900;
  text-align:center;
  }
  #main {
  max-with:960px;
  margin:auto;
  }
  #menu  {
  float:left;
  width:240px;
  background-color:#FF3366;
  }
  #contenu {
  margin-left:245px;
  position: absolute;
  top: 50%;
  left: 40%;
  transform: translate(-50%, -50%);
  }
  #footer {
  background-color:#669933;
  text-align:center;
  clear:both;
  }

  button {
    display: inline-block;
    background-color: #585858;
    border-radius: 10px;
    border: 4px double #cccccc;
    color: #eeeeee;
    text-align: center;
    font-size: 28px;
    padding: 20px;
    width: 500px;
    transition: all 0.5s;
    cursor: pointer;
    margin: 15px;
    }
    button span {
    cursor: pointer;
    display: inline-block;
    position: relative;
    transition: 0.5s;
    }
    button span:after {
    content: '\00bb';
    position: absolute;
    opacity: 0;
    top: 0;
    right: -20px;
    transition: 0.5s;
    }
    button:hover {
    background-color: #f2849e
    }
    button:hover span {
    padding-right: 25px;
    }
    button:hover span:after {
    opacity: 1;
    right: 0;
    }