ul {
    list-style-type: none;

    margin: 0;

    padding: 0;

    width: 300px;

    background-color: #34495e;

}

ul li{
  position:relative;
}

li a {
    display: block;

    color:white;

    padding: 8px 16px;

    text-decoration: none;

    border:1px solid silver;
}

li a:hover {

    background-color: #f39c12;

    color: white;
}

li:hover ul{

display:block;
}

ul li ul{
  position:absolute;

  left:300px;

  top:0;
  
  display:none;
}