ul{
   
    justify-content: center;
}
.menu{
    width: 300px;
     background-color: #000000;
}
a {
    text-decoration: none;
    color: white;
    display: block;
    padding: 15px 10px;
    font-size: 20px;
    transition: 0.2s;
    border-bottom: 1px solid #FFF;
   
   
}
a:hover{
    background-color: #808080;
    border-radius: 5px;
}
li{position: relative}
.submenu{
    position: absolute;
    display: none;
 
   top: 0%;
   left: 100%;
    background: #000000;
   width: 150px;
   list-style-type:none;
   

}
li:hover >.submenu{
    display: block;
    }