Navigation hover style change. please help!

I am learning css and right now i have a theme installed in wordpress 3.0 version, problem is that the hover is so dark that it is nearly impossible to see at which page we are. here is styleheet

/* 2.2 Navigation */
#navigation{font-size:11px;}

#navigation ul.rss{background:url(images/ico-rss.png) no-repeat 0 5px;padding:6px 0 3px 15px;}
#navigation ul.rss li{display:inline;padding:0 10px;}

ul#nav { margin-top:9px; }
#nav, #nav ul  { z-index:100; margin:0; padding:0; list-style:none; line-height:1; }
#nav a  { display:block; z-index:100; padding:0 10px; line-height:28px; font-size:17px; color:#fff; text-decoration:none;}
#nav li  { float:left; width: auto; padding:2px 5px;}
#nav li:hover, #nav li.current_page_item { background: #222; }
#nav li li.current_page_item { background: none; }

/* 2.2.1 Drop-down menus */
#nav li ul  { position: absolute; left: -999em; width: 172px; background: #FFF; border:1px solid #efefef;}
#nav li ul li  { border: 1px solid #efefef; border-width: 0 0 1px; padding:0; }
#nav li ul li a  { background:url(images/ico-bullet.png) no-repeat 5px 10px; width:145px; padding-left:15px; line-height:30px; font-size:12px; color:#000; }
#nav li ul li:hover  { background:#fafafa; }
#nav li ul  { padding:5px; }
#nav li ul ul  { margin: -25px 0 0 120px; }
#nav li ul li ul li a  { border-width: 0 0 1px; }
#nav li:hover ul ul, #nav li.sfhover ul ul, #nav li:hover ul ul ul, #nav li.sfhover ul ul ul { left:-999em; }
#nav li:hover ul,#nav li li:hover ul,#nav li li li:hover ul,#nav li.sfhover ul,#nav li li.sfhover ul,#nav li li li.sfhover ul  { left:auto; }
#nav li:hover,#nav li.hover  { position:static; }

#nav .sf-sub-indicator {display:none;}

i have already tried changing
#nav li ul li:hover { background:#fafafa; } but nothing happened, my domain is https://www.gaxup.com
thanks for reading