.bandeau {
        background-color: greenyellow;
        border: 1px solid grey;
        text-align: center;
        padding: 0px;
      }
      .menu-principal {
        display: inline-block;
        position: relative;
      }
      .menu-principal div {
        background-color: green;
        color: white;
        cursor: pointer;
        padding: 20px;
        font-size: 20px;
      }
      .menu-principal div:hover {
        background-color: limegreen;
      }
      .menu-principal:hover .sous-menu {
        display: block;
      }
      .sous-menu {
        display: none;
        position: absolute;
        top: 63px;
        left: 0px;
        padding: 0px;
      }
      .sous-menu li {
        display: block;
        background-color: limegreen;
        color: white;
        text-decoration: none;
        cursor: pointer;
        padding: 20px;
        width: 150px;
      }
      .sous-menu li:hover {
        background-color: lime;
      }