Tighten up vertical spacing of notebook list.

IPython/html/static/style/ipython.min.css

@@ -38,7 +38,7 @@ div.traceback-wrapper{text-align:left;max-width:800px;margin:auto}
 .list_container>div:last-child{border:none}
 .list_item:hover .list_item{background-color:#ddd}
 .list_item a{text-decoration:none}
-.list_item .span12{padding:5px}
+.list_item .span12{padding:4px}
 .item_name{line-height:24px}
 .item_icon{font-size:14px;color:#5e5e5e;margin-left:5px;margin-right:8px}
 .list_container>div>span,.list_container>div>div{padding:8px}

IPython/html/static/style/style.min.css

@@ -1315,7 +1315,7 @@ span#login_widget{float:right}
 .list_container>div:last-child{border:none}
 .list_item:hover .list_item{background-color:#ddd}
 .list_item a{text-decoration:none}
-.list_item .span12{padding:5px}
+.list_item .span12{padding:4px}
 .item_name{line-height:24px}
 .item_icon{font-size:14px;color:#5e5e5e;margin-left:5px;margin-right:8px}
 .list_container>div>span,.list_container>div>div{padding:8px}

IPython/html/static/tree/less/tree.less

@@ -49,7 +49,7 @@
     background-color: #ddd;
   };
   a {text-decoration: none;}
-  .span12 {padding: 5px;}
+  .span12 {padding: 4px;}
 }
 
 .item_name {