Add zoom animation to background image.

zoom-banner.css

#main-banner {
	background-size:55% auto;
	background-position:center 0;
}

zoom-banner.js

function zoomInBanner(zoomItem, first, second, timing){
	$(zoomItem).animate({ 'background-size' : first }, timing)
    .animate({ 'background-size' : second }, timing,
    function(){
    setTimeout(zoomInBanner(zoomItem, first, second), 4000);
  });
}

$(document).ready(function(){
  // set id or class of element, zoom to percentage, reset zoom (same value in CSS), and timing
  zoomInBanner('#main-banner', '65%', '55%', 8000);
});