diff --git a/core/misc/vertical-tabs.js b/core/misc/vertical-tabs.js
index 14d0660..6240c84 100644
--- a/core/misc/vertical-tabs.js
+++ b/core/misc/vertical-tabs.js
@@ -11,185 +11,191 @@
  * 'verticalTabCallback' (with jQuery.data() attached to the fieldset),
  * which is called every time the user performs an update to a form
  * element inside the tab pane.
+ *
+ * These functions are only run when the viewport width of 660px
  */
-Drupal.behaviors.verticalTabs = {
-  attach: function (context) {
-    $('.vertical-tabs-panes', context).once('vertical-tabs', function () {
-      var focusID = $(':hidden.vertical-tabs-active-tab', this).val();
-      var tab_focus;
-
-      // Check if there are some fieldsets that can be converted to vertical-tabs
-      var $fieldsets = $('> fieldset', this);
-      if ($fieldsets.length == 0) {
-        return;
-      }
 
-      // Create the tab column.
-      var tab_list = $('<ul class="vertical-tabs-list"></ul>');
-      $(this).wrap('<div class="vertical-tabs clearfix"></div>').before(tab_list);
+if (document.documentElement.clientWidth > 640) {
 
-      // Transform each fieldset into a tab.
-      $fieldsets.each(function () {
-        var vertical_tab = new Drupal.verticalTab({
-          title: $('> legend', this).text(),
-          fieldset: $(this)
-        });
-        tab_list.append(vertical_tab.item);
-        $(this)
-          .removeClass('collapsible collapsed')
-          .addClass('vertical-tabs-pane')
-          .data('verticalTab', vertical_tab);
-        if (this.id == focusID) {
-          tab_focus = $(this);
+  Drupal.behaviors.verticalTabs = {
+    attach: function (context) {
+      $('.vertical-tabs-panes', context).once('vertical-tabs', function () {
+        var focusID = $(':hidden.vertical-tabs-active-tab', this).val();
+        var tab_focus;
+
+        // Check if there are some fieldsets that can be converted to vertical-tabs
+        var $fieldsets = $('> fieldset', this);
+        if ($fieldsets.length == 0) {
+          return;
         }
-      });
 
-      $('> li:first', tab_list).addClass('first');
-      $('> li:last', tab_list).addClass('last');
+        // Create the tab column.
+        var tab_list = $('<ul class="vertical-tabs-list"></ul>');
+        $(this).wrap('<div class="vertical-tabs clearfix"></div>').before(tab_list);
+
+        // Transform each fieldset into a tab.
+        $fieldsets.each(function () {
+          var vertical_tab = new Drupal.verticalTab({
+            title: $('> legend', this).text(),
+            fieldset: $(this)
+          });
+          tab_list.append(vertical_tab.item);
+          $(this)
+            .removeClass('collapsible collapsed')
+            .addClass('vertical-tabs-pane')
+            .data('verticalTab', vertical_tab);
+          if (this.id == focusID) {
+            tab_focus = $(this);
+          }
+        });
 
-      if (!tab_focus) {
-        // If the current URL has a fragment and one of the tabs contains an
-        // element that matches the URL fragment, activate that tab.
-        if (window.location.hash && $(window.location.hash, this).length) {
-          tab_focus = $(window.location.hash, this).closest('.vertical-tabs-pane');
+        $('> li:first', tab_list).addClass('first');
+        $('> li:last', tab_list).addClass('last');
+
+        if (!tab_focus) {
+          // If the current URL has a fragment and one of the tabs contains an
+          // element that matches the URL fragment, activate that tab.
+          if (window.location.hash && $(window.location.hash, this).length) {
+            tab_focus = $(window.location.hash, this).closest('.vertical-tabs-pane');
+          }
+          else {
+            tab_focus = $('> .vertical-tabs-pane:first', this);
+          }
         }
-        else {
-          tab_focus = $('> .vertical-tabs-pane:first', this);
+        if (tab_focus.length) {
+          tab_focus.data('verticalTab').focus();
         }
-      }
-      if (tab_focus.length) {
-        tab_focus.data('verticalTab').focus();
-      }
-    });
-  }
-};
-
-/**
- * The vertical tab object represents a single tab within a tab group.
- *
- * @param settings
- *   An object with the following keys:
- *   - title: The name of the tab.
- *   - fieldset: The jQuery object of the fieldset that is the tab pane.
- */
-Drupal.verticalTab = function (settings) {
-  var self = this;
-  $.extend(this, settings, Drupal.theme('verticalTab', settings));
-
-  this.link.click(function () {
-    self.focus();
-    return false;
-  });
-
-  // Keyboard events added:
-  // Pressing the Enter key will open the tab pane.
-  this.link.keydown(function(event) {
-    if (event.keyCode == 13) {
-      self.focus();
-      // Set focus on the first input field of the visible fieldset/tab pane.
-      $("fieldset.vertical-tabs-pane :input:visible:enabled:first").focus();
-      return false;
+      });
     }
-  });
+  };
 
-  this.fieldset
-    .bind('summaryUpdated', function () {
-      self.updateSummary();
-    })
-    .trigger('summaryUpdated');
-};
-
-Drupal.verticalTab.prototype = {
   /**
-   * Displays the tab's content pane.
+   * The vertical tab object represents a single tab within a tab group.
+   *
+   * @param settings
+   *   An object with the following keys:
+   *   - title: The name of the tab.
+   *   - fieldset: The jQuery object of the fieldset that is the tab pane.
    */
-  focus: function () {
-    this.fieldset
-      .siblings('fieldset.vertical-tabs-pane')
-        .each(function () {
-          var tab = $(this).data('verticalTab');
-          tab.fieldset.hide();
-          tab.item.removeClass('selected');
-        })
-        .end()
-      .show()
-      .siblings(':hidden.vertical-tabs-active-tab')
-        .val(this.fieldset.attr('id'));
-    this.item.addClass('selected');
-    // Mark the active tab for screen readers.
-    $('#active-vertical-tab').remove();
-    this.link.append('<span id="active-vertical-tab" class="element-invisible">' + Drupal.t('(active tab)') + '</span>');
-  },
+  Drupal.verticalTab = function (settings) {
+    var self = this;
+    $.extend(this, settings, Drupal.theme('verticalTab', settings));
 
-  /**
-   * Updates the tab's summary.
-   */
-  updateSummary: function () {
-    this.summary.html(this.fieldset.drupalGetSummary());
-  },
+    this.link.click(function () {
+      self.focus();
+      return false;
+    });
 
-  /**
-   * Shows a vertical tab pane.
-   */
-  tabShow: function () {
-    // Display the tab.
-    this.item.show();
-    // Update .first marker for items. We need recurse from parent to retain the
-    // actual DOM element order as jQuery implements sortOrder, but not as public
-    // method.
-    this.item.parent().children('.vertical-tab-button').removeClass('first')
-      .filter(':visible:first').addClass('first');
-    // Display the fieldset.
-    this.fieldset.removeClass('vertical-tab-hidden').show();
-    // Focus this tab.
-    this.focus();
-    return this;
-  },
+    // Keyboard events added:
+    // Pressing the Enter key will open the tab pane.
+    this.link.keydown(function(event) {
+      if (event.keyCode == 13) {
+        self.focus();
+        // Set focus on the first input field of the visible fieldset/tab pane.
+        $("fieldset.vertical-tabs-pane :input:visible:enabled:first").focus();
+        return false;
+      }
+    });
 
-  /**
-   * Hides a vertical tab pane.
-   */
-  tabHide: function () {
-    // Hide this tab.
-    this.item.hide();
-    // Update .first marker for items. We need recurse from parent to retain the
-    // actual DOM element order as jQuery implements sortOrder, but not as public
-    // method.
-    this.item.parent().children('.vertical-tab-button').removeClass('first')
-      .filter(':visible:first').addClass('first');
-    // Hide the fieldset.
-    this.fieldset.addClass('vertical-tab-hidden').hide();
-    // Focus the first visible tab (if there is one).
-    var $firstTab = this.fieldset.siblings('.vertical-tabs-pane:not(.vertical-tab-hidden):first');
-    if ($firstTab.length) {
-      $firstTab.data('verticalTab').focus();
+    this.fieldset
+      .bind('summaryUpdated', function () {
+        self.updateSummary();
+      })
+      .trigger('summaryUpdated');
+  };
+
+  Drupal.verticalTab.prototype = {
+    /**
+     * Displays the tab's content pane.
+     */
+    focus: function () {
+      this.fieldset
+        .siblings('fieldset.vertical-tabs-pane')
+          .each(function () {
+            var tab = $(this).data('verticalTab');
+            tab.fieldset.hide();
+            tab.item.removeClass('selected');
+          })
+          .end()
+        .show()
+        .siblings(':hidden.vertical-tabs-active-tab')
+          .val(this.fieldset.attr('id'));
+      this.item.addClass('selected');
+      // Mark the active tab for screen readers.
+      $('#active-vertical-tab').remove();
+      this.link.append('<span id="active-vertical-tab" class="element-invisible">' + Drupal.t('(active tab)') + '</span>');
+    },
+
+    /**
+     * Updates the tab's summary.
+     */
+    updateSummary: function () {
+      this.summary.html(this.fieldset.drupalGetSummary());
+    },
+
+    /**
+     * Shows a vertical tab pane.
+     */
+    tabShow: function () {
+      // Display the tab.
+      this.item.show();
+      // Update .first marker for items. We need recurse from parent to retain the
+      // actual DOM element order as jQuery implements sortOrder, but not as public
+      // method.
+      this.item.parent().children('.vertical-tab-button').removeClass('first')
+        .filter(':visible:first').addClass('first');
+      // Display the fieldset.
+      this.fieldset.removeClass('vertical-tab-hidden').show();
+      // Focus this tab.
+      this.focus();
+      return this;
+    },
+
+    /**
+     * Hides a vertical tab pane.
+     */
+    tabHide: function () {
+      // Hide this tab.
+      this.item.hide();
+      // Update .first marker for items. We need recurse from parent to retain the
+      // actual DOM element order as jQuery implements sortOrder, but not as public
+      // method.
+      this.item.parent().children('.vertical-tab-button').removeClass('first')
+        .filter(':visible:first').addClass('first');
+      // Hide the fieldset.
+      this.fieldset.addClass('vertical-tab-hidden').hide();
+      // Focus the first visible tab (if there is one).
+      var $firstTab = this.fieldset.siblings('.vertical-tabs-pane:not(.vertical-tab-hidden):first');
+      if ($firstTab.length) {
+        $firstTab.data('verticalTab').focus();
+      }
+      return this;
     }
-    return this;
-  }
-};
+  };
 
-/**
- * Theme function for a vertical tab.
- *
- * @param settings
- *   An object with the following keys:
- *   - title: The name of the tab.
- * @return
- *   This function has to return an object with at least these keys:
- *   - item: The root tab jQuery element
- *   - link: The anchor tag that acts as the clickable area of the tab
- *       (jQuery version)
- *   - summary: The jQuery element that contains the tab summary
- */
-Drupal.theme.prototype.verticalTab = function (settings) {
-  var tab = {};
-  tab.item = $('<li class="vertical-tab-button" tabindex="-1"></li>')
-    .append(tab.link = $('<a href="#"></a>')
-      .append(tab.title = $('<strong></strong>').text(settings.title))
-      .append(tab.summary = $('<span class="summary"></span>')
-    )
-  );
-  return tab;
-};
+  /**
+   * Theme function for a vertical tab.
+   *
+   * @param settings
+   *   An object with the following keys:
+   *   - title: The name of the tab.
+   * @return
+   *   This function has to return an object with at least these keys:
+   *   - item: The root tab jQuery element
+   *   - link: The anchor tag that acts as the clickable area of the tab
+   *       (jQuery version)
+   *   - summary: The jQuery element that contains the tab summary
+   */
+  Drupal.theme.prototype.verticalTab = function (settings) {
+    var tab = {};
+    tab.item = $('<li class="vertical-tab-button" tabindex="-1"></li>')
+      .append(tab.link = $('<a href="#"></a>')
+        .append(tab.title = $('<strong></strong>').text(settings.title))
+        .append(tab.summary = $('<span class="summary"></span>')
+      )
+    );
+    return tab;
+  };
+}
 
 })(jQuery);