nav ul {
    display: flex;
    flex-direction: column;    
    list-style-type: none; 
    margin: 0;     
}

nav ul a {
    color: var(--txmain);
    text-decoration: none;
}                                               
nav ul a:hover {
    color: #69f;
}

nav ul li ul a {
    color: var(--txmain);
}

nav button {
    background: var(--bgmain);
    min-width: 1em;
    width: 2em;
}

nav button:hover {
    background: var(--bgmain);
}