how to make li elements centered ?

header{

    position: fixed;
    left: 0;
    right: 0;

}
header p{
    background-color: tomato;
    margin: auto;
    max-width: 70ch;
}
.header{
    display: flex;
    flex-direction: column;
    background-color: tomato;
    margin: auto;
    max-width: 70ch;
    height: 0;
    overflow: hidden;
    transition: .3s ease-in;
}
.header li{
   max-width: fit-content;
   margin: auto;
   list-style-type: none;
}
.opened{
    height: auto;
}