Navigation Highlight OnePager

	//Navigation Highlight
	var sections = {},
		_height  = $(window).height(),
		i        = 0;

	// Grab positions of our sections
	$('section').each(function(){
		sections[this.id] = $(this).offset().top;
	});

	$(document).scroll(function(){
		var $this = $(this),
			pos   = $this.scrollTop();

		for(i in sections){
			if(sections[i] > pos && sections[i] < pos + _height){
				$('a').removeClass('active');
				$('.nav_' + i).addClass('active');
			}
		}
	});