@media only screen and (max-width: 350px) {

    button {
        display: block;
        width: 100px;
    }
    .btn_abrir{
        display: flex;
        background-color: #ffffff;
        width: 50px;
       position: absolute;
       left: 250px;
       border-color: #ffffff;
    }
    .btn_cerrar{
        left: 250px;
    }
    .nav {
        display: none;
    }
    #hm_element1,
#hm_element2,
#hm_element3,
#hm_element4
{
font-size: 14px;
}
}