ul{
    list-style-type: none;
    margin: 0;
    padding: 0;
    width: 180px;
    height: 100vh;
    background-color: red;
    position: fixed;
    top: 0;
    left: 0;
    overflow-x: hidden;
}

li a{
    display:block;
    color:white;
    text-align:center;
    padding:4px 16px;
    text-decoration:none;
    font-size: 20px;
    margin-top: 20px;
    display: block;
    color: white;
    text-align: left;
    padding: 12px 16px;
    text-decoration: none;
    font-size: 20px;
    margin-top: 0;
}
li a:hover{
    background-color:darkred;
}

header{
    text-align: center;
    margin-left: 180px;
}

.nav{
    background-color: lightgreen;
    padding: 10px;
}