fix css checkbox vertical align, closes #8065

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

@@ -8715,7 +8715,7 b' ul.breadcrumb span {'
   vertical-align: baseline;
   line-height: 22px;
   position: relative;
-  top: 1px;
+  top: -1px;
 }
 .list_header > div .item_link,
 .list_item > div .item_link {

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

@@ -114,7 +114,7 b' ul.breadcrumb {'
         vertical-align: baseline;
         line-height: @btn_mini_height;
         position: relative;
-        top: 1px;
+        top: -1px;
     }
 
     .item_link {