Mon fichier css ne fonctionne pas

@charset "utf-8";
/* CSS Document */

body{
	text-align:justify;
	line-height:19px;
	margin-left: 0px;
	margin-top: 0px;
	margin-right: 0px;
	margin-bottom: 0px;
	background:url(../images/bg-esthetique_01.png) repeat-x #FFF;
	font-size:12px;
	color:#828282;
	font-family:Arial, Helvetica, sans-serif;
}
div.logo{
	float: left;
    height: 98px;
    margin-top: 21px;
    padding-bottom: 24px;
    padding-left: 23px;
    padding-top: 0;
    width: 170px;
	
}


#left_menu {
	float:left;
}
#left_menu ul{
	list-style: none;
    margin:0;
	padding:0}
#left_menu ul li {
    display:block; 
	padding: 0;
	margin:0;
}

@media screen and (max-width:500px){
.left_menu {display:none; }
}

<link href="css/style.css" rel="stylesheet" type="text/css" />