nav {
    position: relative;
    z-index: 100;
}

/* Hamburger icon positioning */
#menuToggle {
    display: block;
    position: absolute;
    top: 5px;
    left: 10px;
    z-index: 100;
    -webkit-user-select: none;
    user-select: none;
}

#menuToggle input {
    display: block;
    width: 40px;
    height: 32px;
    position: absolute;
    top: 0;
    left: 0;
    cursor: pointer;
    opacity: 0;
    z-index: 2;
}

/* Only target the three spans that form the hamburger icon. */
#menuToggle > span {
    display: block;
    width: 30px;
    height: 4px;
    margin-bottom: 5px;
    position: relative;
    background: #ffffff;
    border-radius: 3px;
    transform-origin: 4px 0;
    transition:
        transform 0.5s cubic-bezier(0.77, 0.2, 0.05, 1),
        background 0.5s cubic-bezier(0.77, 0.2, 0.05, 1),
        opacity 0.55s ease;
}

#menuToggle input:checked + span {
    opacity: 1;
    transform: rotate(45deg) translate(-2px, -1px);
    background: #ffffff;
}

#menuToggle input:checked + span:nth-last-child(3) {
    opacity: 0;
    transform: rotate(0deg) scale(0.2, 0.2);
}

#menuToggle input:checked + span:nth-last-child(2) {
    transform: rotate(-45deg) translate(0, -1px);
}

/* Main menu */
#menu {
    position: absolute;
    top: 30px;
    left: 10px;
    width: 220px;
    margin: 0;
    padding: 15px;
    display: none;
    background: rgba(0, 0, 0, 0.9);
    border-radius: 8px;
    box-shadow: 0 4px 10px rgba(0, 0, 0, 0.5);
    z-index: 1000;
}

#menuToggle input:checked ~ #menu {
    display: block;
}

#menu li {
    list-style: none;
    margin: 10px 0;
}

#menu li a {
    color: #ffffff;
    font-size: 110%;
    text-decoration: none;
}

#menu li a:link,
#menu li a:visited {
    color: #ffffff;
}

#menu li a:hover,
#menu li a:active {
    color: #ffffff;
    text-decoration: underline;
}

/* Therapy heading and submenu */
#menu .menu-heading > span {
    display: inline;
    color: #ffffff;
    font-size: 110%;
}

#menu .submenu {
    margin: 5px 0 0 15px;
    padding: 0;
}

#menu .submenu li {
    margin: 5px 0;
}

#menu .submenu li a {
    font-size: 100%;
}

@media (max-width: 600px) {
    #menu li {
        margin: 5px 0;
    }
}