Sticky navigation on the bottom

You could try this:

#site-navigation {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
}

Thank you.
Is it possible to add some elements below navigation something footer-ish such as copyright.

So it's always sticky as well?

Yes it is.

Try this:

.site-info,
#primary-navigation {
    position: fixed;
    left: 0;
    right: 0;
}

.site-info {
    bottom: 0;
}

#primary-navigation {
    bottom: 40px; /* height of copyright bar */
}

Works. Thank you.
Is it possible to show mobile navigation to opposite direction?
top to bottom -> bottom to top

Not sure I understand. Are you wanting the navigation to be stuck on top while on mobile?

My bad,
I thought mobile menu still opens downward but actually it opens upward when it's on the bottom..
So no problem.

Actually it was not mobile menu, desktop menu still opens downward even though it's on the bottom.

Ah, the regular dropdown menu you mean? Can you link me to the site?

Yes, regular dropdown.

Add this:

.main-navigation ul ul {
    top: auto;
    bottom: 60px;
}

.dropdown-menu-toggle:before {
    content: "\f106";
}

Worked!
Awesome :)

Glad I could help :)