bookout=new Image (47,32)
 bookout.src="assets/img/book_out.gif"
 bookover=new Image (47,32)
 bookover.src="assets/img/book_over.gif"
 homeout=new Image (51,32)
 homeout.src="assets/img/home_out.gif"
 homeover=new Image (51,32)
 homeover.src="assets/img/home_over.gif"
 contactout=new Image (48,32)
 contactout.src="assets/img/contact_out.gif"
 contactover=new Image (48,32)
 contactover.src="assets/img/contact_over.gif"