/* Login overlay */
  #loginScreen { display: flex; position:fixed; inset:0; background:#1a1a2e; z-index:9999;
    align-items:center; justify-content:center; }
  #loginBox { background:#fff; border-radius:18px; padding:40px 36px; width:100%; max-width:360px;
    box-shadow:0 8px 40px rgba(0,0,0,.35); }
  #loginBox h4 { margin-bottom:24px; font-weight:700; color:#1a1a2e; }
  #loginError { display:none; }