@media (max-width: 900px) {
  .site-header .nav-wrap {
    max-height: calc(100vh - 40px);
    max-height: calc(100dvh - 40px);
    overflow-y: auto;
    overscroll-behavior: contain;
    -webkit-overflow-scrolling: touch;
    touch-action: pan-y;
  }
}