_s theme small-menu (responsive) not showing

I am using _s theme as a base and I am finding that the js/small-menu.js that supposed to make the menu a toggled dropdown on mobile sites does not show a dropdown menu at all, just “Menu”.
Here’s the CSS:

@media screen and (max-width: 600px) {
	.menu-toggle,
	.main-small-navigation ul.nav-menu.toggled-on {
		display: block;
		margin-left: 80px;
		color: #fff;
		font-family:Verdana, Geneva, sans-serif;

	}

	.navigation-main ul {
		display:none;
	}

	}

Thanks for any suggestions!