diff --git a/blockly_uncompressed.js b/blockly_uncompressed.js
index 2957e6dad..645574f57 100644
--- a/blockly_uncompressed.js
+++ b/blockly_uncompressed.js
@@ -114,7 +114,7 @@ goog.addDependency('../../core/menu.js', ['Blockly.Menu'], ['Blockly.browserEven
 goog.addDependency('../../core/menuitem.js', ['Blockly.MenuItem'], ['Blockly.utils.IdGenerator', 'Blockly.utils.aria', 'Blockly.utils.dom'], {});
 goog.addDependency('../../core/metrics_manager.js', ['Blockly.FlyoutMetricsManager', 'Blockly.MetricsManager'], ['Blockly.IMetricsManager', 'Blockly.registry', 'Blockly.utils.Size', 'Blockly.utils.toolbox'], {'lang': 'es5'});
 goog.addDependency('../../core/msg.js', ['Blockly.Msg'], ['Blockly.utils.global'], {});
-goog.addDependency('../../core/mutator.js', ['Blockly.Mutator'], ['Blockly.Bubble', 'Blockly.Events', 'Blockly.Events.BlockChange', 'Blockly.Events.BubbleOpen', 'Blockly.Icon', 'Blockly.WorkspaceSvg', 'Blockly.Xml', 'Blockly.utils', 'Blockly.utils.Svg', 'Blockly.utils.dom', 'Blockly.utils.object', 'Blockly.utils.toolbox', 'Blockly.utils.xml'], {});
+goog.addDependency('../../core/mutator.js', ['Blockly.Mutator'], ['Blockly.Bubble', 'Blockly.Events', 'Blockly.Events.BlockChange', 'Blockly.Events.BubbleOpen', 'Blockly.Icon', 'Blockly.Options', 'Blockly.WorkspaceSvg', 'Blockly.Xml', 'Blockly.utils', 'Blockly.utils.Svg', 'Blockly.utils.dom', 'Blockly.utils.object', 'Blockly.utils.toolbox', 'Blockly.utils.xml'], {});
 goog.addDependency('../../core/names.js', ['Blockly.Names'], ['Blockly.Msg', 'Blockly.constants'], {});
 goog.addDependency('../../core/options.js', ['Blockly.Options'], ['Blockly.Theme', 'Blockly.Themes.Classic', 'Blockly.registry', 'Blockly.utils.IdGenerator', 'Blockly.utils.Metrics', 'Blockly.utils.toolbox'], {});
 goog.addDependency('../../core/plugin_manager.js', ['Blockly.PluginManager'], [], {});
@@ -126,7 +126,7 @@ goog.addDependency('../../core/renderers/common/constants.js', ['Blockly.blockRe
 goog.addDependency('../../core/renderers/common/debugger.js', ['Blockly.blockRendering.Debug'], ['Blockly.blockRendering.Measurable', 'Blockly.blockRendering.RenderInfo', 'Blockly.blockRendering.Row', 'Blockly.blockRendering.Types', 'Blockly.connectionTypes', 'Blockly.constants', 'Blockly.utils.Svg', 'Blockly.utils.dom'], {'lang': 'es5'});
 goog.addDependency('../../core/renderers/common/drawer.js', ['Blockly.blockRendering.Drawer'], ['Blockly.blockRendering.RenderInfo', 'Blockly.blockRendering.Row', 'Blockly.blockRendering.Types', 'Blockly.utils.svgPaths'], {});
 goog.addDependency('../../core/renderers/common/i_path_object.js', ['Blockly.blockRendering.IPathObject'], [], {});
-goog.addDependency('../../core/renderers/common/info.js', ['Blockly.blockRendering.RenderInfo'], ['Blockly.blockRendering.BottomRow', 'Blockly.blockRendering.ExternalValueInput', 'Blockly.blockRendering.Hat', 'Blockly.blockRendering.InRowSpacer', 'Blockly.blockRendering.InlineInput', 'Blockly.blockRendering.InputRow', 'Blockly.blockRendering.Measurable', 'Blockly.blockRendering.NextConnection', 'Blockly.blockRendering.OutputConnection', 'Blockly.blockRendering.PreviousConnection', 'Blockly.blockRendering.RoundCorner', 'Blockly.blockRendering.Row', 'Blockly.blockRendering.SpacerRow', 'Blockly.blockRendering.SquareCorner', 'Blockly.blockRendering.StatementInput', 'Blockly.blockRendering.TopRow', 'Blockly.blockRendering.Types', 'Blockly.constants', 'Blockly.inputTypes'], {});
+goog.addDependency('../../core/renderers/common/info.js', ['Blockly.blockRendering.RenderInfo'], ['Blockly.blockRendering.BottomRow', 'Blockly.blockRendering.ExternalValueInput', 'Blockly.blockRendering.Field', 'Blockly.blockRendering.Hat', 'Blockly.blockRendering.InRowSpacer', 'Blockly.blockRendering.InlineInput', 'Blockly.blockRendering.InputRow', 'Blockly.blockRendering.JaggedEdge', 'Blockly.blockRendering.Measurable', 'Blockly.blockRendering.NextConnection', 'Blockly.blockRendering.OutputConnection', 'Blockly.blockRendering.PreviousConnection', 'Blockly.blockRendering.RoundCorner', 'Blockly.blockRendering.Row', 'Blockly.blockRendering.SpacerRow', 'Blockly.blockRendering.SquareCorner', 'Blockly.blockRendering.StatementInput', 'Blockly.blockRendering.TopRow', 'Blockly.blockRendering.Types', 'Blockly.constants', 'Blockly.inputTypes'], {});
 goog.addDependency('../../core/renderers/common/marker_svg.js', ['Blockly.blockRendering.MarkerSvg'], ['Blockly.ASTNode', 'Blockly.Events', 'Blockly.Events.MarkerMove', 'Blockly.connectionTypes', 'Blockly.constants', 'Blockly.utils.Svg', 'Blockly.utils.dom'], {});
 goog.addDependency('../../core/renderers/common/path_object.js', ['Blockly.blockRendering.PathObject'], ['Blockly.Theme', 'Blockly.blockRendering.ConstantProvider', 'Blockly.blockRendering.IPathObject', 'Blockly.utils.Svg', 'Blockly.utils.dom'], {});
 goog.addDependency('../../core/renderers/common/renderer.js', ['Blockly.blockRendering.Renderer'], ['Blockly.IRegistrable', 'Blockly.InsertionMarkerManager', 'Blockly.blockRendering.ConstantProvider', 'Blockly.blockRendering.Debug', 'Blockly.blockRendering.Drawer', 'Blockly.blockRendering.IPathObject', 'Blockly.blockRendering.MarkerSvg', 'Blockly.blockRendering.PathObject', 'Blockly.blockRendering.RenderInfo', 'Blockly.connectionTypes', 'Blockly.constants'], {});
@@ -159,28 +159,26 @@ goog.addDependency('../../core/renderers/zelos/measurables/row_elements.js', ['B
 goog.addDependency('../../core/renderers/zelos/measurables/rows.js', ['Blockly.zelos.BottomRow', 'Blockly.zelos.TopRow'], ['Blockly.blockRendering.BottomRow', 'Blockly.blockRendering.TopRow', 'Blockly.utils.object'], {});
 goog.addDependency('../../core/renderers/zelos/path_object.js', ['Blockly.zelos.PathObject'], ['Blockly.blockRendering.PathObject', 'Blockly.utils.Svg', 'Blockly.utils.dom', 'Blockly.utils.object', 'Blockly.zelos.ConstantProvider'], {});
 goog.addDependency('../../core/renderers/zelos/renderer.js', ['Blockly.zelos.Renderer'], ['Blockly.InsertionMarkerManager', 'Blockly.blockRendering', 'Blockly.blockRendering.Renderer', 'Blockly.connectionTypes', 'Blockly.constants', 'Blockly.utils.object', 'Blockly.zelos.ConstantProvider', 'Blockly.zelos.Drawer', 'Blockly.zelos.MarkerSvg', 'Blockly.zelos.PathObject', 'Blockly.zelos.RenderInfo'], {});
-goog.addDependency('../../core/requires.js', ['Blockly.requires'], ['Blockly', 'Blockly.Comment', 'Blockly.ContextMenuItems', 'Blockly.FieldAngle', 'Blockly.FieldCheckbox', 'Blockly.FieldColour', 'Blockly.FieldDropdown', 'Blockly.FieldImage', 'Blockly.FieldLabelSerializable', 'Blockly.FieldMultilineInput', 'Blockly.FieldNumber', 'Blockly.FieldTextInput', 'Blockly.FieldVariable', 'Blockly.FlyoutButton', 'Blockly.Generator', 'Blockly.HorizontalFlyout', 'Blockly.Mutator', 'Blockly.ShortcutItems', 'Blockly.Themes.Classic', 'Blockly.Themes.Dark', 'Blockly.Themes.Deuteranopia', 'Blockly.Themes.HighContrast', 'Blockly.Themes.Tritanopia', 'Blockly.Toolbox', 'Blockly.Trashcan', 'Blockly.VariablesDynamic', 'Blockly.VerticalFlyout', 'Blockly.Warning', 'Blockly.ZoomControls', 'Blockly.geras.Renderer', 'Blockly.thrasos.Renderer', 'Blockly.zelos.Renderer'], {});
+goog.addDependency('../../core/requires.js', ['Blockly.requires'], ['Blockly', 'Blockly.Comment', 'Blockly.ContextMenuItems', 'Blockly.FieldAngle', 'Blockly.FieldCheckbox', 'Blockly.FieldColour', 'Blockly.FieldDropdown', 'Blockly.FieldImage', 'Blockly.FieldLabelSerializable', 'Blockly.FieldMultilineInput', 'Blockly.FieldNumber', 'Blockly.FieldTextInput', 'Blockly.FieldVariable', 'Blockly.FlyoutButton', 'Blockly.Generator', 'Blockly.HorizontalFlyout', 'Blockly.Mutator', 'Blockly.ShortcutItems', 'Blockly.Themes.Classic', 'Blockly.Themes.Deuteranopia', 'Blockly.Themes.HighContrast', 'Blockly.Themes.Tritanopia', 'Blockly.Toolbox', 'Blockly.Trashcan', 'Blockly.VariablesDynamic', 'Blockly.VerticalFlyout', 'Blockly.Warning', 'Blockly.ZoomControls', 'Blockly.geras.Renderer', 'Blockly.thrasos.Renderer', 'Blockly.zelos.Renderer'], {});
 goog.addDependency('../../core/scrollbar.js', ['Blockly.Scrollbar', 'Blockly.ScrollbarPair'], ['Blockly.Events', 'Blockly.Touch', 'Blockly.browserEvents', 'Blockly.utils', 'Blockly.utils.Coordinate', 'Blockly.utils.Metrics', 'Blockly.utils.Svg', 'Blockly.utils.dom'], {});
 goog.addDependency('../../core/shortcut_items.js', ['Blockly.ShortcutItems'], ['Blockly.Gesture', 'Blockly.ShortcutRegistry', 'Blockly.utils.KeyCodes'], {});
 goog.addDependency('../../core/shortcut_registry.js', ['Blockly.ShortcutRegistry'], ['Blockly.utils.KeyCodes', 'Blockly.utils.object'], {});
 goog.addDependency('../../core/theme.js', ['Blockly.Theme'], ['Blockly.registry', 'Blockly.utils', 'Blockly.utils.object'], {});
 goog.addDependency('../../core/theme/classic.js', ['Blockly.Themes.Classic'], ['Blockly.Theme'], {});
-goog.addDependency('../../core/theme/dark.js', ['Blockly.Themes.Dark'], ['Blockly.Theme'], {});
 goog.addDependency('../../core/theme/deuteranopia.js', ['Blockly.Themes.Deuteranopia'], ['Blockly.Theme'], {});
 goog.addDependency('../../core/theme/highcontrast.js', ['Blockly.Themes.HighContrast'], ['Blockly.Theme'], {});
-goog.addDependency('../../core/theme/modern.js', ['Blockly.Themes.Modern'], ['Blockly.Theme'], {});
 goog.addDependency('../../core/theme/tritanopia.js', ['Blockly.Themes.Tritanopia'], ['Blockly.Theme'], {});
 goog.addDependency('../../core/theme/zelos.js', ['Blockly.Themes.Zelos'], ['Blockly.Theme'], {});
 goog.addDependency('../../core/theme_manager.js', ['Blockly.ThemeManager'], ['Blockly.Theme'], {});
 goog.addDependency('../../core/toolbox/category.js', ['Blockly.ToolboxCategory'], ['Blockly.ToolboxItem', 'Blockly.registry', 'Blockly.utils', 'Blockly.utils.aria', 'Blockly.utils.dom', 'Blockly.utils.object', 'Blockly.utils.toolbox'], {'lang': 'es5'});
 goog.addDependency('../../core/toolbox/collapsible_category.js', ['Blockly.CollapsibleToolboxCategory'], ['Blockly.ToolboxCategory', 'Blockly.ToolboxItem', 'Blockly.ToolboxSeparator', 'Blockly.registry', 'Blockly.utils.aria', 'Blockly.utils.dom', 'Blockly.utils.object', 'Blockly.utils.toolbox'], {});
 goog.addDependency('../../core/toolbox/separator.js', ['Blockly.ToolboxSeparator'], ['Blockly.ToolboxItem', 'Blockly.registry', 'Blockly.utils.dom'], {'lang': 'es5'});
-goog.addDependency('../../core/toolbox/toolbox.js', ['Blockly.Toolbox'], ['Blockly.CollapsibleToolboxCategory', 'Blockly.Css', 'Blockly.Events', 'Blockly.Events.ToolboxItemSelect', 'Blockly.Touch', 'Blockly.browserEvents', 'Blockly.constants', 'Blockly.registry', 'Blockly.utils', 'Blockly.utils.Rect', 'Blockly.utils.aria', 'Blockly.utils.dom', 'Blockly.utils.toolbox'], {'lang': 'es5'});
+goog.addDependency('../../core/toolbox/toolbox.js', ['Blockly.Toolbox'], ['Blockly.CollapsibleToolboxCategory', 'Blockly.Css', 'Blockly.Events', 'Blockly.Events.ToolboxItemSelect', 'Blockly.Options', 'Blockly.Touch', 'Blockly.browserEvents', 'Blockly.constants', 'Blockly.registry', 'Blockly.utils', 'Blockly.utils.Rect', 'Blockly.utils.aria', 'Blockly.utils.dom', 'Blockly.utils.toolbox'], {'lang': 'es5'});
 goog.addDependency('../../core/toolbox/toolbox_item.js', ['Blockly.ToolboxItem'], [], {});
 goog.addDependency('../../core/tooltip.js', ['Blockly.Tooltip'], ['Blockly.browserEvents', 'Blockly.utils.string'], {});
 goog.addDependency('../../core/touch.js', ['Blockly.Touch'], ['Blockly.constants', 'Blockly.utils', 'Blockly.utils.global', 'Blockly.utils.string'], {});
 goog.addDependency('../../core/touch_gesture.js', ['Blockly.TouchGesture'], ['Blockly.Gesture', 'Blockly.browserEvents', 'Blockly.utils', 'Blockly.utils.Coordinate', 'Blockly.utils.object'], {});
-goog.addDependency('../../core/trashcan.js', ['Blockly.Trashcan'], ['Blockly.Events', 'Blockly.Events.TrashcanOpen', 'Blockly.IPositionable', 'Blockly.Scrollbar', 'Blockly.Xml', 'Blockly.browserEvents', 'Blockly.constants', 'Blockly.registry', 'Blockly.utils.Rect', 'Blockly.utils.Svg', 'Blockly.utils.dom', 'Blockly.utils.math', 'Blockly.utils.toolbox'], {'lang': 'es5'});
+goog.addDependency('../../core/trashcan.js', ['Blockly.Trashcan'], ['Blockly.Events', 'Blockly.Events.TrashcanOpen', 'Blockly.IPositionable', 'Blockly.Options', 'Blockly.Scrollbar', 'Blockly.Xml', 'Blockly.browserEvents', 'Blockly.constants', 'Blockly.registry', 'Blockly.utils.Rect', 'Blockly.utils.Svg', 'Blockly.utils.dom', 'Blockly.utils.math', 'Blockly.utils.toolbox'], {'lang': 'es5'});
 goog.addDependency('../../core/utils.js', ['Blockly.utils'], ['Blockly.Msg', 'Blockly.constants', 'Blockly.utils.Coordinate', 'Blockly.utils.Rect', 'Blockly.utils.colour', 'Blockly.utils.global', 'Blockly.utils.string', 'Blockly.utils.style', 'Blockly.utils.userAgent'], {});
 goog.addDependency('../../core/utils/aria.js', ['Blockly.utils.aria'], [], {});
 goog.addDependency('../../core/utils/colour.js', ['Blockly.utils.colour'], [], {});
diff --git a/core/requires.js b/core/requires.js
index f08286ec4..009ab3f9c 100644
--- a/core/requires.js
+++ b/core/requires.js
@@ -82,8 +82,6 @@ goog.require('Blockly.zelos.Renderer');
 // Blockly Themes.
 // Classic is the default theme.
 goog.require('Blockly.Themes.Classic');
-goog.require('Blockly.Themes.Dark');
 goog.require('Blockly.Themes.Deuteranopia');
 goog.require('Blockly.Themes.HighContrast');
 goog.require('Blockly.Themes.Tritanopia');
-// goog.require('Blockly.Themes.Modern');
diff --git a/core/theme/dark.js b/core/theme/dark.js
deleted file mode 100644
index 398497660..000000000
--- a/core/theme/dark.js
+++ /dev/null
@@ -1,33 +0,0 @@
-/**
- * @license
- * Copyright 2019 Google LLC
- * SPDX-License-Identifier: Apache-2.0
- */
-
-/**
- * @fileoverview Dark theme.
- * @author samelh@google.com (Sam El-Husseini)
- */
-'use strict';
-
-goog.provide('Blockly.Themes.Dark');
-
-goog.require('Blockly.Theme');
-
-Blockly.Themes.Dark = Blockly.Theme.defineTheme('dark', {
-  'base': Blockly.Themes.Classic,
-  'componentStyles': {
-    'workspaceBackgroundColour': '#1e1e1e',
-    'toolboxBackgroundColour': 'blackBackground',
-    'toolboxForegroundColour': '#fff',
-    'flyoutBackgroundColour': '#252526',
-    'flyoutForegroundColour': '#ccc',
-    'flyoutOpacity': 1,
-    'scrollbarColour': '#797979',
-    'insertionMarkerColour': '#fff',
-    'insertionMarkerOpacity': 0.3,
-    'scrollbarOpacity': 0.4,
-    'cursorColour': '#d0d0d0',
-    'blackBackground': '#333'
-  }
-});
diff --git a/core/theme/modern.js b/core/theme/modern.js
deleted file mode 100644
index 2ed8a6845..000000000
--- a/core/theme/modern.js
+++ /dev/null
@@ -1,108 +0,0 @@
-/**
- * @license
- * Copyright 2018 Google LLC
- * SPDX-License-Identifier: Apache-2.0
- */
-
-/**
- * @fileoverview Modern theme.
- * Same colours as classic, but single coloured border.
- */
-'use strict';
-
-goog.provide('Blockly.Themes.Modern');
-
-goog.require('Blockly.Theme');
-
-
-// Temporary holding object.
-Blockly.Themes.Modern = {};
-
-Blockly.Themes.Modern.defaultBlockStyles = {
-  "colour_blocks": {
-    "colourPrimary": "#a5745b",
-    "colourSecondary": "#dbc7bd",
-    "colourTertiary": "#845d49"
-  },
-  "list_blocks": {
-    "colourPrimary": "#745ba5",
-    "colourSecondary": "#c7bddb",
-    "colourTertiary": "#5d4984"
-  },
-  "logic_blocks": {
-    "colourPrimary": "#5b80a5",
-    "colourSecondary": "#bdccdb",
-    "colourTertiary": "#496684"
-  },
-  "loop_blocks": {
-    "colourPrimary": "#5ba55b",
-    "colourSecondary": "#bddbbd",
-    "colourTertiary": "#498449"
-  },
-  "math_blocks": {
-    "colourPrimary": "#5b67a5",
-    "colourSecondary": "#bdc2db",
-    "colourTertiary": "#495284"
-  },
-  "procedure_blocks": {
-    "colourPrimary": "#995ba5",
-    "colourSecondary": "#d6bddb",
-    "colourTertiary": "#7a4984"
-  },
-  "text_blocks": {
-    "colourPrimary": "#5ba58c",
-    "colourSecondary": "#bddbd1",
-    "colourTertiary": "#498470"
-  },
-  "variable_blocks": {
-    "colourPrimary": "#a55b99",
-    "colourSecondary": "#dbbdd6",
-    "colourTertiary": "#84497a"
-  },
-  "variable_dynamic_blocks": {
-    "colourPrimary": "#a55b99",
-    "colourSecondary": "#dbbdd6",
-    "colourTertiary": "#84497a"
-  },
-  "hat_blocks": {
-    "colourPrimary": "#a55b99",
-    "colourSecondary": "#dbbdd6",
-    "colourTertiary": "#84497a",
-    "hat": "cap"
-  }
-};
-
-Blockly.Themes.Modern.categoryStyles = {
-  "colour_category": {
-    "colour": "#a5745b"
-  },
-  "list_category": {
-    "colour": "#745ba5"
-  },
-  "logic_category": {
-    "colour": "#5b80a5"
-  },
-  "loop_category": {
-    "colour": "#5ba55b"
-  },
-  "math_category": {
-    "colour": "#5b67a5"
-  },
-  "procedure_category": {
-    "colour": "#995ba5"
-  },
-  "text_category": {
-    "colour": "#5ba58c"
-  },
-  "variable_category": {
-    "colour": "#a55b99"
-  },
-  "variable_dynamic_category": {
-    "colour": "#a55b99"
-  }
-};
-
-// This style is still being fleshed out and may change.
-Blockly.Themes.Modern =
-    new Blockly.Theme('modern', Blockly.Themes.Modern.defaultBlockStyles,
-        Blockly.Themes.Modern.categoryStyles);
diff --git a/package.json b/package.json
index af5104ba5..cd4643d37 100644
--- a/package.json
+++ b/package.json
@@ -63,6 +63,7 @@
   "devDependencies": {
     "@blockly/block-test": "^1.0.0",
     "@blockly/dev-tools": "^2.0.1",
+    "@blockly/theme-dark": "^1.0.0",
     "@blockly/theme-modern": "^2.1.1",
     "babel-eslint": "^10.1.0",
     "chai": "^4.2.0",
diff --git a/scripts/gulpfiles/appengine_tasks.js b/scripts/gulpfiles/appengine_tasks.js
index 08fb3ea85..e07b9f60f 100644
--- a/scripts/gulpfiles/appengine_tasks.js
+++ b/scripts/gulpfiles/appengine_tasks.js
@@ -59,6 +59,7 @@ function copyAppengineSrc() {
 function copyPlaygroundDeps() {
   const playgroundDeps = [
       './node_modules/@blockly/dev-tools/dist/index.js',
+      './node_modules/@blockly/theme-dark/dist/index.js',
       './node_modules/@blockly/theme-modern/dist/index.js',
       './node_modules/@blockly/block-test/dist/index.js',
   ];
diff --git a/tests/playgrounds/advanced_playground.html b/tests/playgrounds/advanced_playground.html
index b142a6a00..87e1f37e2 100644
--- a/tests/playgrounds/advanced_playground.html
+++ b/tests/playgrounds/advanced_playground.html
@@ -67,6 +67,7 @@
 <script src="../themes/test_themes.js"></script>
 <script src="./screenshot.js"></script>
 <script src="../../node_modules/@blockly/dev-tools/dist/index.js"></script>
+<script src="../../node_modules/@blockly/theme-dark/dist/index.js"></script>
 <script src="../../node_modules/@blockly/theme-modern/dist/index.js"></script>
 
 <script>