highlighting current page in css

I’ve tried to get WP to highlight the page currently selected in the menu bar by using

.current_page_item {
  color:green;

in my stylesheet, yet for some reason it won’t highlight. I can highlight the background colour but not actually the text itself.

here is my CSS:

a {

	color: #FEE886;

}

a img {

	border: none;

}

a:visited {

	color: #FEE886;

}

a:hover {

	color: #9a8;

}

*{margin:0; padding:0; list-style-type: none;}
body{background: #ccc url(/wordpress/images/tile_bg.jpg) repeat;
	font: normal 12px Arial, Helvetica, Geneva, sans-serif;
	text-align: center;
}
h1{color: #FEE886; font-size: 18px; margin:0; text-align:right;
	text-transform: uppercase;
	font-weight: normal;
	font-style: normal;
}
h2{font-size: 12px; font-weight:normal; color: #FEE886; margin:5px 0 10px;
	text-transform: uppercase;
}
.current_page_item {
  color:green;
}
#container{background: #0A0A0A; width:750px;
	text-align: left;
	text-align: left;
	color: #d8d8d8;
	margin-right: auto;
	margin-top: 20px;
	margin-left: auto;
	padding: 20px;
}
#sidebar{float:left; width: 110px;
	background-color: #0A0A0A;
	text-align: center;
	font: 18px Georgia, "Times New Roman", Times, serif;
	color: #7f7f7f;
}

#sidebar a {
	color: #7f7f7f;
	text-decoration: none;
	list-style-type: none;
}

#sidebar a:hover {
	color: #ccc;
	text-decoration: none;
	list-style-type: none;

}
#main{float:right; width: 620px;
	background-color: #0A0A0A;
	color: #d8d8d8;
	margin: 10px;
	line-height: 17px;
}
#footer{clear:both; text-align: center;
	font-size: 10px;
	color: #707070;
}