diff --git a/packages/devextreme/testing/tests/DevExpress.ui.widgets.treeList/rowDragging.tests.js b/packages/devextreme/testing/tests/DevExpress.ui.widgets.treeList/rowDragging.tests.js
index fe9affa2aefc..55bbe5373241 100644
--- a/packages/devextreme/testing/tests/DevExpress.ui.widgets.treeList/rowDragging.tests.js
+++ b/packages/devextreme/testing/tests/DevExpress.ui.widgets.treeList/rowDragging.tests.js
@@ -1,3 +1,12 @@
+import 'fluent_blue_light.css!';
+
+import 'ui/data_grid';
+import 'ui/tree_list';
+
+import $ from 'jquery';
+import pointerMock from '../../helpers/pointerMock.js';
+import { setupTreeListModules } from '../../helpers/treeListMocks.js';
+
 QUnit.testStart(function() {
     const markup =
         `<style>
@@ -16,15 +25,6 @@ QUnit.testStart(function() {
     $('#qunit-fixture').html(markup);
 });
 
-import 'generic_light.css!';
-
-import 'ui/data_grid';
-import 'ui/tree_list';
-
-import $ from 'jquery';
-import pointerMock from '../../helpers/pointerMock.js';
-import { setupTreeListModules } from '../../helpers/treeListMocks.js';
-
 const generateData = function(rowCount) {
     let i;
     const result = [];
@@ -100,7 +100,7 @@ QUnit.module('Drag and Drop nodes', moduleConfig, () => {
         rowsView.render($testElement);
 
         // act
-        const pointer = pointerMock(rowsView.getRowElement(0)).start().down().move(0, 70);
+        const pointer = pointerMock(rowsView.getRowElement(0)).start().down().move(0, 100);
 
         // assert
         const $draggableElement = $('body').children('.dx-sortable-dragging');
@@ -130,7 +130,7 @@ QUnit.module('Drag and Drop nodes', moduleConfig, () => {
         rowsView.render($testElement);
 
         // act
-        const pointer = pointerMock(rowsView.getRowElement(0)).start().down().move(0, 50);
+        const pointer = pointerMock(rowsView.getRowElement(0)).start().down().move(0, 75);
 
         // assert
         const $placeholderElement = $('body').children('.dx-sortable-placeholder');
diff --git a/packages/devextreme/testing/tests/DevExpress.ui.widgets.treeList/treeList.tests.js b/packages/devextreme/testing/tests/DevExpress.ui.widgets.treeList/treeList.tests.js
index 27612718b794..ab5e5f26f328 100644
--- a/packages/devextreme/testing/tests/DevExpress.ui.widgets.treeList/treeList.tests.js
+++ b/packages/devextreme/testing/tests/DevExpress.ui.widgets.treeList/treeList.tests.js
@@ -1,17 +1,4 @@
-QUnit.testStart(function() {
-    const markup =
-        '<!--qunit-fixture-->\
-    <div id="container">\
-        <div id="treeList">\
-        </div>\
-    </div>\
-';
-
-    $('#qunit-fixture').html(markup);
-    // $('body').append(markup);
-});
-
-import 'generic_light.css!';
+import 'fluent_blue_light.css!';
 import $ from 'jquery';
 import { noop } from 'core/utils/common';
 import devices from '__internal/core/m_devices';
@@ -25,6 +12,18 @@ import pointerMock from '../../helpers/pointerMock.js';
 import { CLICK_EVENT } from '../../helpers/grid/keyboardNavigationHelper.js';
 import { createEvent } from 'common/core/events/utils/index';
 
+QUnit.testStart(function() {
+    const markup =
+        '<!--qunit-fixture-->\
+    <div id="container">\
+        <div id="treeList">\
+        </div>\
+    </div>\
+';
+
+    $('#qunit-fixture').html(markup);
+});
+
 fx.off = true;
 
 const defaultModuleConfig = {
@@ -937,7 +936,7 @@ QUnit.module('Option Changed', defaultModuleConfig, () => {
     // T576806
     QUnit.test('Pages should be correctly loaded after change dataSource and selectedRowKeys options', function(assert) {
         const treeList = createTreeList({
-            height: 1500,
+            height: 2160,
             autoExpandAll: true
         });
 
@@ -1454,7 +1453,7 @@ QUnit.module('Focused Row', defaultModuleConfig, () => {
     QUnit.test('TreeList with focusedRowKey', function(assert) {
         // arrange, act
         const treeList = createTreeList({
-            height: 105,
+            height: 170,
             keyExpr: 'id',
             dataSource: generateData(10),
             paging: {
@@ -1478,7 +1477,7 @@ QUnit.module('Focused Row', defaultModuleConfig, () => {
     QUnit.test('TreeList with remoteOperations and focusedRowKey', function(assert) {
         // arrange, act
         const treeList = createTreeList({
-            height: 105,
+            height: 170,
             keyExpr: 'id',
             dataSource: generateData(10),
             remoteOperations: true,
diff --git a/packages/devextreme/testing/tests/DevExpress.ui.widgets.treeList/virtualScrolling.integration.tests.js b/packages/devextreme/testing/tests/DevExpress.ui.widgets.treeList/virtualScrolling.integration.tests.js
index 64d431edc6d6..1afee373e326 100644
--- a/packages/devextreme/testing/tests/DevExpress.ui.widgets.treeList/virtualScrolling.integration.tests.js
+++ b/packages/devextreme/testing/tests/DevExpress.ui.widgets.treeList/virtualScrolling.integration.tests.js
@@ -4,7 +4,7 @@ import $ from 'jquery';
 import { TreeListWrapper } from '../../helpers/wrappers/dataGridWrappers.js';
 import { generateNestedData } from '../../helpers/treeListMocks.js';
 
-import 'generic_light.css!';
+import 'fluent_blue_light.css!';
 
 const treeListWrapper = new TreeListWrapper('#treeList');
 
@@ -58,7 +58,7 @@ QUnit.module('Virtual Scrolling', baseModuleConfig, () => {
 
         const treeList = $('#treeList').dxTreeList({
             dataSource: data,
-            height: 500,
+            height: 720,
             autoExpandAll: true,
             wordWrapEnabled: true,
             columns: [{
diff --git a/packages/devextreme/testing/tests/DevExpress.ui.widgets/gantt.tests.js b/packages/devextreme/testing/tests/DevExpress.ui.widgets/gantt.tests.js
index 39756f7394ce..eab5ccfdbd9f 100644
--- a/packages/devextreme/testing/tests/DevExpress.ui.widgets/gantt.tests.js
+++ b/packages/devextreme/testing/tests/DevExpress.ui.widgets/gantt.tests.js
@@ -1,5 +1,5 @@
 import $ from 'jquery';
-import 'generic_light.css!';
+import 'fluent_blue_light.css!';
 import 'gantt.css!';
 import 'ui/gantt';
 
diff --git a/packages/devextreme/testing/tests/DevExpress.ui.widgets/ganttParts/dataSource.tests.js b/packages/devextreme/testing/tests/DevExpress.ui.widgets/ganttParts/dataSource.tests.js
index d96970bc412f..12886123bb02 100644
--- a/packages/devextreme/testing/tests/DevExpress.ui.widgets/ganttParts/dataSource.tests.js
+++ b/packages/devextreme/testing/tests/DevExpress.ui.widgets/ganttParts/dataSource.tests.js
@@ -58,9 +58,15 @@ QUnit.module('DataSources', moduleConfig, () => {
         assert.equal(updatedTask.end, dataToUpdate.end, 'new task end is updated');
     });
     test('removing', function(assert) {
-        this.createInstance(options.allSourcesOptions);
-        this.instance.option('editing.enabled', true);
-        this.instance.option('selectedRowKey', 3);
+        this.createInstance({
+            ...options.allSourcesOptions,
+            // explicit height: the treeList is virtual, so the inserted task must fit the render window
+            height: 700,
+            selectedRowKey: 3,
+            editing: {
+                enabled: true,
+            },
+        });
         this.clock.tick(10);
 
         const removedTaskId = 3;
@@ -116,9 +122,15 @@ QUnit.module('DataSources', moduleConfig, () => {
             { dataField: 'progress', caption: 'progress' },
             { dataField: 'end', caption: 'End Date' }
         ];
-        this.createInstance(options.allSourcesOptions);
-        this.instance.option('columns', columns);
-        this.instance.option('editing.enabled', true);
+        this.createInstance({
+            ...options.allSourcesOptions,
+            // explicit height: the treeList is virtual, so the inserted task must fit the render window
+            height: 700,
+            columns,
+            editing: {
+                enabled: true,
+            },
+        });
         this.clock.tick(10);
         const taskData = {
             start: new Date('2019-02-21'),