main nav always open

Would you still want to be able to open/close it, or do you just want it to be open all the time?

Open at all times... Something else I've noticed about the main nav and the secondary, is that the rule says text-align:left but it aligns center when the mobile menus are horizontal. Do you know what would cause this?

First, add this CSS:

@media (max-width: 768px) {
    .main-navigation .menu-toggle {
        display: none;
    }
}

Then, add this PHP:

add_filter( 'generate_navigation_class','tu_navigation_classes' );
function tu_navigation_classes( $classes ) {
	$classes[] = 'toggled';
	return $classes;
}

That should do it :)