Javascript non pris en compte

<!DOCTYPE html>
<html>
 <head>
  
  <meta charset="utf=8"/>
  
  <link rel="stylesheet" type="text/css"  href="Site 1 css.css"></link>
 
  <script type="text/javascript" src="site.js"></script>
  
  <title>Premier Site</title>
  
 </head>
 
 <body>
  
  <div></div>
  
 </body>
 
</html>

body {
 background-color : violet;
}

div {
 height : 200px;
 width : 200px;
 background-color: #efefef;
}

$(document).ready(function() {
 $("div").hide("slow");
});