#tb { position: absolute; left: 0px; center: 0px; bottom: 0px;text-align:left; width: 100%; }
div > div#tb { position: fixed; }
#tb1 { position: absolute; left: 0px; center: 0px; top: 0px;text-align:left; width: 100%;}
div > div#tb1 { position: fixed; }