diff --git a/core/misc/displace.js b/core/misc/displace.js
new file mode 100644
index 0000000..9f34545
--- /dev/null
+++ b/core/misc/displace.js
@@ -0,0 +1,189 @@
+/**
+ * Manages elements that can offset the size of the viewport.
+ */
+(function (window, Drupal, $) {
+
+  var offsets = {
+    top: 0,
+    right: 0,
+    bottom: 0,
+    left: 0
+  };
+
+  var displacingElements = {
+    top: [],
+    right: [],
+    bottom: [],
+    left: []
+  }
+
+  /**
+   * Informs listeners of the current offset dimensions.
+   */
+  function displace() {
+    calculateOffsets();
+    $(document).trigger('drupalViewportOffsetChange', offsets);
+  }
+
+  /**
+   * Returns the current offset dimensions.
+   */
+  displace.getOffsets = function (refresh) {
+    if (refresh) {
+      calculateOffsets();
+    }
+    return offsets;
+  };
+
+  /**
+   * Registers elements that should be used to determine viewport offset sizes.
+   */
+  displace.registerElements = function (elementsByEdge) {
+    // Go through each edge in elementsByEdge.
+    for (var edge in elementsByEdge) {
+      if (elementsByEdge.hasOwnProperty(edge)) {
+        // Each element or set of elements must be listed under an edge
+        // property.
+        if ($.inArray(edge, ['top', 'right', 'bottom', 'left']) === -1) {
+          continue;
+        }
+        var elements = elementsByEdge[edge];
+        // Wrap the elements in an array if just one element is provided.
+        elements = (!'length' in elements) ? [elements] : elements;
+        // Loop through each element and add it to the list of displacing
+        // elements for the given edge.
+        for (var i = 0, n = elements.length; i < n; i++) {
+          // The elements will be stored as DOM nodes for consistency.
+          var el = ('get' in elements[i]) ? elements[i].get() : elements[i];
+          displacingElements[edge].push(el);
+        }
+        // Sort the displacing elements for the edge and remove duplicates.
+        displacingElements[edge] = $.unique(displacingElements[edge]);
+      }
+    }
+  };
+
+  /**
+   * Removes elements from the list of displacing elements for an edge.
+   *
+   * @param elementsByEdge
+   *  Either an object like displacingElements variable
+   *  or an edge (edge will remove all elements assigned to it)
+   */
+  displace.removeElements = function (elementsByEdge) {
+    // Check if only edge is given
+    if ($.inArray(elementsByEdge, ['top', 'right', 'bottom', 'left']) !== -1) {
+      displacingElements[elementsByEdge] = [];
+    }
+    // Remove elements by edge
+    else {
+      // Go through each edge in elementsByEdge.
+      for (var edge in elementsByEdge) {
+        if (elementsByEdge.hasOwnProperty(edge)) {
+          // Each element or set of elements must be listed under an edge
+          // property.
+          if ($.inArray(edge, ['top', 'right', 'bottom', 'left']) === -1) {
+            continue;
+          }
+          // Array of elements that will be removed
+          var remove = [];
+          var elements = elementsByEdge[edge];
+          // Wrap the elements in an array if just one element is provided.
+          elements = (!'length' in elements) ? [elements] : elements;
+          // Loop through each element and add it to the list of displacing
+          // elements for the given edge.
+          for (var i = 0, n = elements.length; i < n; i++) {
+            // The elements will be stored as DOM nodes for consistency.
+            var el = ('get' in elements[i]) ? elements[i].get() : elements[i];
+            remove.push(el);
+          }
+          // Now remove elements from displacingElements
+          displacingElements[edge] = $.grep(displacingElements[edge], function(el) {
+            return $.inArray(el, remove) === -1;
+          });
+        }
+      }
+    }
+  };
+
+  /**
+   * Returns the object that lists the displacing elements by edge.
+   */
+  displace.getElements = function () {
+    return displacingElements;
+  };
+
+  /**
+   * Determines the viewport offsets.
+   */
+  function calculateOffsets () {
+    // Go through each edge and add up the displacements.
+    for (var edge in displacingElements) {
+      if (displacingElements.hasOwnProperty(edge)) {
+        var displacement = 0;
+        // Perform the calculations on a local varialbe
+        var offset = 0;
+        // Go through the displacing elements on each edge and calculate the
+        // offset.
+        for (var i = 0, n = displacingElements[edge].length; i < n; i++) {
+          var $el = $(displacingElements[edge][i]);
+          // If the element is not visble, do not use its dimensions.
+          if (!$el.is(':visible')) {
+            continue;
+          }
+          // If the offset data attribute contains a displacing value, use it.
+          displacement = parseInt($el.attr('data-offset-' + edge), 10);
+          // If the element's offset data attribute does not contain a value,
+          // try to get the displacing dimension from the element directly.
+          if (typeof displacement === 'undefined' || typeof displacement !== 'number' || isNaN(displacement) || displacement < 0) {
+            var size = 0;
+            var docSize = 0;
+            // Get the offset of the element itself.
+            var placement = $el.offset()[(edge === 'left' || edge === 'right') ? 'left' : 'top'];
+            // Subtract scroll distance from placement to get the distance
+            // to the edge of the viewport.
+            placement = placement - window['scroll' + ((edge === 'right' || edge === 'left') ? 'X' : 'Y')];
+            // Find the displacement value according to the edge.
+            switch (edge) {
+              // Left and top elements displace as a sum of their own offset value
+              // plus their size.
+              case 'top':
+                size = $el.outerHeight();
+                // Total displacment is the sum of the elements placement and size.
+                displacement = placement + size;
+                break;
+              case 'left':
+                size = $el.outerWidth();
+                // Total displacment is the sum of the elements placement and size.
+                displacement = placement + size;
+                break;
+              // Right and bottom elements displace according to their left and
+              // top offset. Their size isn't important.
+              case 'bottom':
+                docSize = document.documentElement.clientHeight;
+                displacement = docSize - placement;
+                break;
+              case 'right':
+                docSize = document.documentElement.clientWidth;
+                displacement = docSize - placement;
+                break;
+              default:
+                displacement = 0;
+            }
+          }
+          // If the displacement value is larger than the current value for this
+          // edge, use the value.
+          offset = Math.max(offset, displacement);
+        }
+        // Store the calculated offset
+        offsets[edge] = offset;
+      }
+    }
+  }
+
+  /**
+   * Assign the displace function to a property of the Drupal global object.
+   */
+  Drupal.displace = displace;
+
+}(window, Drupal, jQuery));
diff --git a/core/misc/tableheader.js b/core/misc/tableheader.js
index 0d4f7cd..633dc6e 100644
--- a/core/misc/tableheader.js
+++ b/core/misc/tableheader.js
@@ -1,4 +1,4 @@
-(function ($, Drupal) {
+(function ($, Drupal, window, document) {
 
 "use strict";
 
@@ -17,10 +17,13 @@ function scrollValue(position) {
 
 // Select and initilize sticky table headers.
 function tableHeaderInitHandler(e) {
+  TableHeader.displacements = window.parent.Drupal.displace.getOffsets(true);
   var $tables = $(e.data.context).find('table.sticky-enabled').once('tableheader');
   for (var i = 0, il = $tables.length; i < il; i++) {
     TableHeader.tables.push(new TableHeader($tables[i]));
   }
+  // Trigger a scroll event to prime sticky headers that may be applicable.
+  $(window).trigger('scroll.TableHeader');
 }
 
 // Helper method to loop through tables and execute a method.
@@ -39,16 +42,16 @@ function tableHeaderOnScrollHandler(e) {
   forTables('onScroll');
 }
 
-function tableHeaderOffsetChangeHandler(e) {
+function tableHeaderOffsetChangeHandler(e, offsets) {
   // Compute the new offset value.
-  TableHeader.computeOffsetTop();
-  forTables('stickyPosition', TableHeader.offsetTop);
+  TableHeader.displacements = offsets;
+  forTables('stickyPosition', offsets.top);
 }
 
 // Bind event that need to change all tables.
 $(window).on({
   /**
-   * When resizing table width and offset top can change, recalculate everything.
+   * When resizing table width can change, recalculate everything.
    */
   'resize.TableHeader': tableHeaderResizeHandler,
 
@@ -66,9 +69,9 @@ $(document).on({
   'columnschange.TableHeader': tableHeaderResizeHandler,
 
   /**
-   * Offset value vas changed by a third party script.
+   * Recalculate TableHeader.topOffset when viewport is resized
    */
-  'offsettopchange.TableHeader': tableHeaderOffsetChangeHandler
+  'drupalViewportOffsetChange.TableHeader': tableHeaderOffsetChangeHandler
 });
 
 /**
@@ -77,9 +80,6 @@ $(document).on({
  * TableHeader will make the current table header stick to the top of the page
  * if the table is very long.
  *
- * Fire a custom "topoffsetchange" event to make TableHeader compute the
- * new offset value from the "data-offset-top" attributes of relevant elements.
- *
  * @param table
  *   DOM object for the table to add a sticky header to.
  *
@@ -122,24 +122,15 @@ $.extend(TableHeader, {
   tables: [],
 
   /**
-   * Cache of computed offset value.
+   * Cache of computed viewport displacement values.
    *
    * @type {Number}
    */
-  offsetTop: 0,
-
-  /**
-   * Sum all [data-offset-top] values and cache it.
-   */
-  computeOffsetTop: function () {
-    var $offsets = $('[data-offset-top]');
-    var value, sum = 0;
-    for (var i = 0, il = $offsets.length; i < il; i++) {
-      value = parseInt($offsets[i].getAttribute('data-offset-top'), 10);
-      sum += !isNaN(value) ? value : 0;
-    }
-    this.offsetTop = sum;
-    return sum;
+  displacements: {
+    top: 0,
+    right: 0,
+    bottom: 0,
+    left: 0
   }
 });
 
@@ -211,7 +202,7 @@ $.extend(TableHeader.prototype, {
    */
   checkStickyVisible: function () {
     var scrollTop = scrollValue('scrollTop');
-    var tableTop = this.tableOffset.top - TableHeader.offsetTop;
+    var tableTop = this.tableOffset.top - TableHeader.displacements.top;
     var tableBottom = tableTop + this.tableHeight;
     var visible = false;
 
@@ -230,7 +221,7 @@ $.extend(TableHeader.prototype, {
    *
    * @param event
    */
-  onScroll: function (e) {
+  onScroll: function (event) {
     this.checkStickyVisible();
     // Track horizontal positioning relative to the viewport.
     this.stickyPosition(null, scrollValue('scrollLeft'));
@@ -248,9 +239,8 @@ $.extend(TableHeader.prototype, {
     this.tableHeight = this.$originalTable[0].clientHeight;
 
     // Update offset top.
-    TableHeader.computeOffsetTop();
     this.tableOffset = this.$originalTable.offset();
-    this.stickyPosition(TableHeader.offsetTop);
+    this.stickyPosition(TableHeader.displacements.top, scrollValue('scrollLeft'));
 
     // Update columns width.
     var $that = null;
@@ -277,4 +267,4 @@ $.extend(TableHeader.prototype, {
 // Expose constructor in the public space.
 Drupal.TableHeader = TableHeader;
 
-}(jQuery, Drupal));
+}(jQuery, Drupal, window, window.document));
diff --git a/core/modules/overlay/overlay-child.css b/core/modules/overlay/overlay-child.css
index ecfa4cb..66f07bc 100644
--- a/core/modules/overlay/overlay-child.css
+++ b/core/modules/overlay/overlay-child.css
@@ -16,15 +16,17 @@
 }
 
 #overlay {
-  display: table;
+  box-sizing: border-box;
+  display: block;
   margin: 0 auto;
+  max-width: 80em;
+  max-width: 80rem;
   min-height: 100px;
-  min-width: 700px;
   position: relative;
-  padding: .2em;
   padding-bottom: 2em;
-  padding-right: 26px; /* LTR */
-  width: 88%;
+  padding-left: 40px;
+  padding-right: 40px;
+  width: 100%;
 }
 #overlay-titlebar {
   padding: 0 20px;
diff --git a/core/modules/overlay/overlay-child.js b/core/modules/overlay/overlay-child.js
index 80a8a2f..60964c8 100644
--- a/core/modules/overlay/overlay-child.js
+++ b/core/modules/overlay/overlay-child.js
@@ -3,7 +3,7 @@
  * Attaches the behaviors for the Overlay child pages.
  */
 
-(function ($) {
+(function ($, window, document) {
 
 "use strict";
 
@@ -179,11 +179,4 @@ Drupal.overlayChild.behaviors.shortcutAddLink = function (context, settings) {
   });
 };
 
-// Workaround because of the way jQuery events works.
-// jQuery from the parent frame needs to be used to catch this event.
-parent.jQuery(document).bind('offsettopchange', function () {
-  // Fires an event that the child iframe can listen to.
-  $(document).trigger('offsettopchange');
-});
-
-})(jQuery);
+})(jQuery, window, window.document);
diff --git a/core/modules/overlay/overlay-parent.js b/core/modules/overlay/overlay-parent.js
index caf9336..52de4b4 100644
--- a/core/modules/overlay/overlay-parent.js
+++ b/core/modules/overlay/overlay-parent.js
@@ -34,6 +34,10 @@ Drupal.behaviors.overlayParent = {
       return;
     }
 
+    // The overlay's positioning can be affected by other elements on the page.
+    // Get the current viewpor offset values.
+    Drupal.overlay.viewportOffsets = Drupal.displace.getOffsets(true);
+
     $(document)
       // Instead of binding a click event handler to every link we bind one to
       // the document and only handle events that bubble up. This allows other
@@ -131,6 +135,7 @@ Drupal.overlay.create = function () {
   $(window)
     .bind('resize' + eventClass, $.proxy(this, 'eventhandlerOuterResize'));
   $(document)
+    .on('drupalViewportOffsetChange' + eventClass, $.proxy(this, 'eventhandlerViewportOffsetChange'))
     .bind('drupalOverlayLoad' + eventClass, $.proxy(this, 'eventhandlerOuterResize'))
     .bind('drupalOverlayReady' + eventClass +
           ' drupalOverlayClose' + eventClass, $.proxy(this, 'eventhandlerSyncURLFragment'))
@@ -139,11 +144,9 @@ Drupal.overlay.create = function () {
           ' drupalOverlayBeforeLoad' + eventClass +
           ' drupalOverlayResize' + eventClass, $.proxy(this, 'eventhandlerDispatchEvent'));
 
-  if ($('.overlay-displace-top, .overlay-displace-bottom').length) {
-    $(document)
-      .bind('drupalOverlayResize' + eventClass, $.proxy(this, 'eventhandlerAlterDisplacedElements'))
-      .bind('drupalOverlayClose' + eventClass, $.proxy(this, 'eventhandlerRestoreDisplacedElements'));
-  }
+  $(document)
+    .bind('drupalOverlayResize' + eventClass, $.proxy(this, 'eventhandlerAlterDisplacedElements'))
+    .bind('drupalOverlayClose' + eventClass, $.proxy(this, 'eventhandlerRestoreDisplacedElements'));
 };
 
 /**
@@ -398,6 +401,14 @@ Drupal.overlay.isExternalLink = function (url) {
 };
 
 /**
+ *
+ */
+Drupal.overlay.eventhandlerViewportOffsetChange = function (event, offsets) {
+  Drupal.overlay.viewportOffsets = offsets;
+  Drupal.overlay.eventhandlerOuterResize();
+}
+
+/**
  * Event handler: resizes overlay according to the size of the parent window.
  *
  * @param event
@@ -435,22 +446,28 @@ Drupal.overlay.eventhandlerAlterDisplacedElements = function (event) {
     return;
   }
 
+  var offsets = Drupal.overlay.viewportOffsets;
+
   $(this.iframeWindow.document.body).css({
-    marginTop: Drupal.overlay.getDisplacement('top'),
-    marginBottom: Drupal.overlay.getDisplacement('bottom')
-  }).attr('data-offset-top', Drupal.overlay.getDisplacement('top'));
-
-  $(document).bind('offsettopchange', function () {
-    var iframeDocument = Drupal.overlay.iframeWindow.document;
-    $(iframeDocument.body).attr('data-offset-top', Drupal.overlay.getDisplacement('top'));
-    $(iframeDocument).trigger('offsettopchange');
+    'margin-top': offsets.top,
+    'margin-right': offsets.right,
+    'margin-bottom': offsets.bottom,
+    'margin-left': offsets.left
   });
 
+  $(Drupal.overlay.iframeWindow.document).trigger('drupalViewportOffsetChange', Drupal.overlay.viewportOffsets);
+
   var documentHeight = this.iframeWindow.document.body.clientHeight;
   var documentWidth = this.iframeWindow.document.body.clientWidth;
   // IE6 doesn't support maxWidth, use width instead.
   var maxWidthName = 'maxWidth';
 
+  // If either the documentWidth or documentHeight are a zero dimension, abort
+  // the effort to alter presentation elements.
+  if (documentWidth === 0 || documentHeight === 0) {
+    return;
+  }
+
   if (Drupal.overlay.leftSidedScrollbarOffset === undefined && $(document.documentElement).attr('dir') === 'rtl') {
     // We can't use element.clientLeft to detect whether scrollbars are placed
     // on the left side of the element when direction is set to "rtl" as most
@@ -474,7 +491,7 @@ Drupal.overlay.eventhandlerAlterDisplacedElements = function (event) {
 
   // Consider any element that should be visible above the overlay (such as
   // a toolbar).
-  $('.overlay-displace-top, .overlay-displace-bottom').each(function () {
+  $(Drupal.displace.getElements().top).add(Drupal.displace.getElements().bottom).each(function () {
     var data = $(this).data();
     var maxWidth = documentWidth;
     // In IE, Shadow filter makes element to overlap the scrollbar with 1px.
diff --git a/core/modules/overlay/overlay.module b/core/modules/overlay/overlay.module
index cc29255..197d006 100644
--- a/core/modules/overlay/overlay.module
+++ b/core/modules/overlay/overlay.module
@@ -225,6 +225,7 @@ function overlay_library_info() {
       array('system', 'jquery'),
       array('system', 'drupal'),
       array('system', 'drupalSettings'),
+      array('system', 'drupal.displace'),
       array('system', 'jquery.ui.core'),
       array('system', 'jquery.bbq'),
     ),
diff --git a/core/modules/system/system.module b/core/modules/system/system.module
index 2c51ae0..0523006 100644
--- a/core/modules/system/system.module
+++ b/core/modules/system/system.module
@@ -1380,6 +1380,21 @@ function system_library_info() {
     ),
   );
 
+  // A utility that measures elements like the toolbar that can potentially
+  // displace the positioning of display elements like the overlay.
+  $libraries['drupal.displace'] = array(
+    'title' => 'Drupal displace',
+    'version' => VERSION,
+    'js' => array(
+      'core/misc/displace.js' => array('group' => JS_LIBRARY),
+    ),
+    'dependencies' => array(
+      array('system', 'jquery'),
+      array('system', 'drupal'),
+      array('system', 'drupal.debounce'),
+    ),
+  );
+
   // A utility function to limit calls to a function with a given time.
   $libraries['drupal.debounce'] = array(
     'title' => 'Drupal debounce',
@@ -2076,6 +2091,7 @@ function system_library_info() {
       array('system', 'drupal'),
       array('system', 'drupalSettings'),
       array('system', 'jquery.once'),
+      array('system', 'drupal.displace'),
     ),
   );
   $libraries['drupal.timezone'] = array(
diff --git a/core/modules/toolbar/css/toolbar.base.css b/core/modules/toolbar/css/toolbar.base.css
index 58a2c2b..64e6468 100644
--- a/core/modules/toolbar/css/toolbar.base.css
+++ b/core/modules/toolbar/css/toolbar.base.css
@@ -91,7 +91,7 @@ html.js .toolbar {
   position: absolute;
 }
 .toolbar .tray {
-  z-index: 250;
+  z-index: 1200;
 }
 .toolbar .horizontal {
   width: 100%;
diff --git a/core/modules/toolbar/js/toolbar.js b/core/modules/toolbar/js/toolbar.js
index 45e91ad..33c7133 100644
--- a/core/modules/toolbar/js/toolbar.js
+++ b/core/modules/toolbar/js/toolbar.js
@@ -84,6 +84,12 @@ Drupal.behaviors.toolbar = {
       // Call setHeight on screen resize. Wrap it in debounce to prevent
       // setHeight from being called too frequently.
       var setHeight = Drupal.debounce(Drupal.toolbar.setHeight, 200);
+      // Register elements with Drupal.displace that could affect the size and
+      // placement of other UI components.
+      Drupal.displace.registerElements({
+        top: $toolbar,
+        left: $trays
+      });
       // Attach behavior to the window.
       $(window)
         .on('resize.toolbar', setHeight);
@@ -158,9 +164,9 @@ Drupal.toolbar.toggleTray = function (event) {
       // Set aria-pressed to false.
       .attr('aria-pressed', 'false');
     $toolbar.find('.tray').not($activateTray).removeClass('active');
-    // Update the page and toolbar dimension indicators.
-    updatePeripherals();
   }
+  // Update the page and toolbar dimension indicators.
+  updatePeripherals();
 };
 
 /**
@@ -184,6 +190,9 @@ Drupal.toolbar.setHeight = function () {
   /**
    * Get the height of the active tray and include it in the total
    * height of the toolbar.
+   *
+   * If the height of the bar changed, Drupal.displace is called so that
+   * elements can adjust to the placement of the bar.
    */
   height += $trays.filter('.active.horizontal').outerHeight() || 0;
   // Indicate the height of the toolbar in the attribute data-offset-top.
@@ -192,8 +201,25 @@ Drupal.toolbar.setHeight = function () {
     $toolbar.attr('data-offset-top', height);
     // Alter the padding on the top of the body element.
     $('body').css('padding-top', height);
-    $(document).trigger('offsettopchange', height);
-    $(window).trigger('resize');
+    // Trigger a recalculation of viewport displacing elements.
+    Drupal.displace();
+  }
+};
+
+/**
+ * Sets the width of a vertical tray in a data attribute.
+ *
+ * If the width of the tray changed, Drupal.displace is called so that elements
+ * can adjust to the placement of the tray.
+ */
+Drupal.toolbar.setTrayWidth = function () {
+  var $tray = $toolbar.find('.tray.active');
+  var trayWidth = $tray.hasClass('vertical') ? $tray.width() : 0;
+  var offset = $tray.attr('data-offset-left');
+  if (offset !== trayWidth) {
+    $tray.attr('data-offset-left', trayWidth);
+    // Trigger a recalculation of viewport displacing elements.
+    Drupal.displace();
   }
 };
 
@@ -296,6 +322,8 @@ function updatePeripherals () {
   setBodyState();
   // Adjust the height of the toolbar.
   Drupal.toolbar.setHeight();
+  // Adjust the tray width for vertical trays.
+  Drupal.toolbar.setTrayWidth();
 }
 
 /**
diff --git a/core/modules/toolbar/toolbar.module b/core/modules/toolbar/toolbar.module
index e4996bc..5cd1f5b 100644
--- a/core/modules/toolbar/toolbar.module
+++ b/core/modules/toolbar/toolbar.module
@@ -93,7 +93,7 @@ function toolbar_element_info() {
       'id' => 'toolbar-administration',
       // The 'overlay-displace-top' class pushes the overlay down, so it appears
       // below the toolbar.
-      'class' => array('toolbar', 'overlay-displace-top'),
+      'class' => array('toolbar',),
       'role' => 'navigation',
     ),
     // Metadata for the administration bar.
@@ -101,7 +101,7 @@ function toolbar_element_info() {
       '#heading' => t('Toolbar items'),
       '#attributes' => array(
         'id' => 'toolbar-bar',
-        'class' => array('bar', 'overlay-displace-top', 'clearfix'),
+        'class' => array('bar', 'clearfix'),
       ),
     ),
   );
@@ -315,7 +315,6 @@ function toolbar_pre_render_item($element) {
     }
     $element['tray']['#wrapper_attributes'] += $attributes;
     $element['tray']['#wrapper_attributes']['class'][] = 'tray';
-    $element['tray']['#wrapper_attributes']['class'][] = 'overlay-displace-top';
 
     if (!isset($element['tray']['#theme_wrappers'])) {
       $element['tray']['#theme_wrappers'] = array();
@@ -631,6 +630,7 @@ function toolbar_library_info() {
       array('system', 'matchmedia'),
       array('system', 'jquery.once'),
       array('system', 'drupal.debounce'),
+      array('system', 'drupal.displace'),
       array('toolbar', 'toolbar.menu'),
     ),
   );
diff --git a/core/themes/bartik/css/style.css b/core/themes/bartik/css/style.css
index 44deab1..67c37d3 100644
--- a/core/themes/bartik/css/style.css
+++ b/core/themes/bartik/css/style.css
@@ -1623,7 +1623,7 @@ div.admin-panel .description {
 /**
  * Responsive tables.
  */
-@media screen and (max-width:28.125em) { /* 450px */
+@media screen and (max-width: 37.5em) { /* 600px */
   th.priority-low,
   td.priority-low,
   th.priority-medium,
@@ -1631,7 +1631,7 @@ div.admin-panel .description {
     display: none;
   }
 }
-@media screen and (max-width:45em) { /* 720px */
+@media screen and (max-width: 60em) { /* 920px */
   th.priority-low,
   td.priority-low {
     display: none;
diff --git a/core/themes/seven/style.css b/core/themes/seven/style.css
index 72ce5e6..6440294 100644
--- a/core/themes/seven/style.css
+++ b/core/themes/seven/style.css
@@ -522,7 +522,7 @@ table.system-status-report tr.error {
 /**
  * Responsive tables.
  */
-@media screen and (max-width:28.125em) { /* 450px */
+@media screen and (max-width: 37.5em) { /* 600px */
   th.priority-low,
   td.priority-low,
   th.priority-medium,
@@ -530,7 +530,7 @@ table.system-status-report tr.error {
     display: none;
   }
 }
-@media screen and (max-width:45em) { /* 720px */
+@media screen and (max-width: 60em) { /* 920px */
   th.priority-low,
   td.priority-low {
     display: none;