function toggle(obj) {
  with (document.getElementById(obj).style) { display = (display == 'none') ? 'block' : 'none'; }
}

if (document.images) {
image1 = new Image
image2 = new Image
image3 = new Image
image4 = new Image
image5 = new Image
image6 = new Image
 
image1.src = "../images/residential-landscaping.jpg"
image2.src = "../images/residential-landscaping-off.jpg"
image3.src = "../images/commercial-landscaping.jpg"
image4.src = "../images/commercial-landscaping-off.jpg"
image5.src = "../images/swimming-pool-design.jpg"
image6.src = "../images/swimming-pool-design-off.jpg"
}