#menu {
    /* width: 30%; */
    width: 40vw;
    /* height: 100%; */
    background: rgba(127, 125, 127, 0.65);
    font-size: 2vw;
    display: inline-block;
    text-align: center;
    margin: 0;
    font-family: Verdana;
    border-radius: 15px;
    position: absolute;
    top: 50%;
    left: 50%;
    margin-right: -50%;
    transform: translate(-50%, -50%);
}

#menu_header {
    font-size: 2.7vw;
    color: white;
    margin-bottom: 30px;
    margin-top: 25px;
    display: block;
    background: black;
    font-weight: bold;
    padding: 5px 0 5px 0;
}

nav {
    margin: 20px;
    cursor: pointer;
    padding: 5px 0 5px 0;
}

nav:hover {
    background: black;
    color: white;
}

/* Для книжной ориентации */
@media screen and (orientation: portrait) { 
    #menu_header {
      font-size: 2.7vh;
    }
    #menu {
        width: 30vh;
        font-size: 2vh;
    }
}