#openMenuBtn {
    position: fixed;
    top: 50%;
    left: 0;
    transform: translateY(-50%);
    writing-mode: vertical-rl;            /* Text vertikal */
    text-orientation: upright;            /* Buchstaben normal */
    padding: 15px 10px;
    background: #fbe6ca;
    color: brown;
    border: none;
    cursor: pointer;
    font-size: 18px;
    z-index: 2000;
    border-radius: 0 20px 20px 0;
    box-shadow: 20px 20px 50px grey;
}

#overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background rgba(165, 42, 42, 0.4); /* brown mit Transparenz */
    opacity: 0;
    pointer-events: none;
    transition: 0.3s ease;
    z-index: 1500;
}

#sideMenu {
    position: fixed;
    top: 0;
    left: -260px;
    width: 260px;
    height: 100%;
    background: #fbe6ca;                                /*#222;*/
    padding-top: 20px;
    transition: 0.3s ease;
    z-index: 2001;

    overflow-y: auto;     /* vertikales Scrollen */
    overflow-x: hidden;   /* kein horizontales Scrollen */
}

#sideMenu a {
    display: block;
    padding: 7px 20px;            /*7px ist der Zeilenabstand, 20px der Abstand vom linken Rand*/
    color: brown;
    text-decoration: none;
    font-size: 18px;
}

#sideMenu a:hover {
   border: 2px solid black;                           /* background:#444;*/
   border-radius: 0 20px 20px 0;
}

#sideMenu.active {
    left: 0;
}

#overlay.active {
    opacity: 1;
    pointer-events: auto;
}