header{
/*    position:relative;*/
}
.mobile_menu_btn{
    position:fixed;
    top:0px;
    left:20px;
    z-index:801;
    width: 45px;
    height: 45px;
    transition: left 0.1s;
    cursor: pointer;
    padding:5px;
    background-color:#000;
    text-align: center;
    padding-top:8px;
}
.mobile_menu_btn i{
    color:white;
    vertical-align: middle;
    font-size:2em;
}