if (document.images) {
   
     button1 = new Image
     button2 = new Image
	 
	 button3 = new Image
     button4 = new Image
	 
	 button5 = new Image
     button6 = new Image
	 
	 button7 = new Image
     button8 = new Image
	 
	 button9 = new Image
     button10 = new Image
	 
	 button11 = new Image
     button12 = new Image	 
	 
	 	 
     button1.src = 'images/home.jpg'
     button2.src = 'images/home-hvr.jpg'
	 
	 button3.src = 'images/about.jpg'
     button4.src = 'images/about-hvr.jpg'
	 
	 button5.src = 'images/safety.jpg'
     button6.src = 'images/safety-hvr.jpg'
	 
	 button7.src = 'images/projects.jpg'
     button8.src = 'images/projects-hvr.jpg'
	 
	 button9.src = 'images/careers.jpg'
     button10.src = 'images/careers-hvr.jpg'
	 
	 button11.src = 'images/contact.jpg'
     button12.src = 'images/contact-hvr.jpg'
 }