Untitled

<div id="nav">

  <ul>

    <li class="menuitem"><a href="">menu 1</a></li>

    <li class="menuitem"><a href="">menu 2</a></li>

    <li class="menuitem"><a href="">menu 3</a></li>

    <li class="menuitem"><a href="">menu 4</a></li>

  </ul>

  <div id="kitten">

    <img src="http://placekitten.com.s3.amazonaws.com/homepage-samples/408/287.jpg" alt="">

  </div>

</div>

.menuitem {

  display: inline-block;

  width: 120px;

}

@media screen and (max-width: 600px) {

 .menuitem {

   display: block;

   background-color: red;

  }

  #kitten {

    display: none;

  }

}