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%; 
}