i am trying to move the postition of my top menu from the right to the left of the page

i changed the float from right to left but nothing happened

.mainlevel-nav, .mainlevel-nav:link, .mainlevel-nav:visited{
float: left;
color: #BBB;
font-size: 11px;
font-family: Verdana, Arial, Helvetica, sans-serif;
text-decoration: none;
padding: 25px 15px 30px 15px;
border-left: 1px solid #DDD;
display: block;