Update index.html

Author: vaithak

index.html

@@ -154,7 +154,7 @@ <h1>The best free Python resources</h1>
          <div class="span4 booksection {{ level }}">
           <a target="_blank" href="{{url}}">
             <div class="view"></div>
-            <div title="{{ title }}" id="cover" style="background:black url('{{cover}}') no-repeat center;-webkit-background-size:cover;-moz-background-size:cover;background-size:cover;z-index:50">
+            <div title="{{ title }}" id="cover" style="background:black url('{{cover}}') no-repeat center;-webkit-background-size:cover;-moz-background-size:cover;background-size:cover">
             </div>
             <h2 title="{{ title }}">{{title}}</h2>
           </a>