header {
    position: fixed;
    width: 100%;
    background: #FFF;
    height: 70px;
    left: 70%;
    transform: translate(-50%, 0);
    background-color: #000;
}

#Menu {
    height: 100%;
    position: relative;
    width: 100%;
    transform: translateX(0px);
    transition: transform 250ms ease-in-out;
    font-size: 25px;
}
.MenuInner{
    margin:0;
    padding:0;
}
.MenuInner li{
    list-style: none;
    display: inline-block;
    background: #000;
    color: #fff;
    cursor: pointer;
}

.MenuInner li:hover{
    background: #fff;
}

.MenuInner li a{
    color: #fff;
    padding: 10px;
    text-decoration: none;
}

.MenuInner li:hover a{
    color: #000;
}