Issue #1704786 by tim.plunkett: Fixed Update seven_css_alter() for jQuery UI update.

core/themes/seven/template.php

@@ -111,7 +111,7 @@ function seven_css_alter(&$css) {
     $css['core/misc/vertical-tabs-rtl.css']['data'] = drupal_get_path('theme', 'seven') . '/vertical-tabs-rtl.css';
   }
   // Use Seven's jQuery UI theme style instead of the default one.
-  if (isset($css['core/misc/ui/jquery.ui.theme.css'])) {
-    $css['core/misc/ui/jquery.ui.theme.css']['data'] = drupal_get_path('theme', 'seven') . '/jquery.ui.theme.css';
+  if (isset($css['core/misc/ui/themes/base/jquery.ui.theme.css'])) {
+    $css['core/misc/ui/themes/base/jquery.ui.theme.css']['data'] = drupal_get_path('theme', 'seven') . '/jquery.ui.theme.css';
   }
 }