[Rise]

aksak1988,

$(document).ready(function() {

	var $a7 = $('#a7');
	
	var colors = ['#ffffff', '#252525'];
	
	var $window = $(window);
	
	$window.scroll(function() {
		
		var top = $window.scrollTop();
		var height = $window.height();
		
		var index, color;

		if (top < height * 5.245) {
			index = 0;
		} else if (top < height * 5.545) {
			index = 1;
		} else if (top < height * 6.315) {
			index = 0;
		} else if (top < height * 7.215) {
			index = 1;
		} else if (top < height * 8.888) {
			index = 0;
		} else {// top > height * 8.888
			index = 1;
		}
		
		color = colors[index];

		$a7.css({// #ffffff.png, #252525.png, ...
			'background-image': 'url(' + color + '.png)',
			'border-color': color
		});
		
	});
	
});