body{ 
margin: 0px; 
overflow: hidden; 
}

.arrow{ 
position: absolute; 
background: none; 
width: 3em; 
height: 3em; 
}

#uArrow{ 
top:0px; 
width: 100%; 
}

#dArrow{ 
bottom:0px; 
width: 100%; 
}

#lArrow{ 
left:0px; 
height: 100%; 
}

#rArrow{ 
right:0px; 
height: 100%; 
}