chrome-devtools-frontend/front_end/panels/elements/StylesSidebarPane.ts

Chrome DevTools UI

// Copyright 2021 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

/*
 * Copyright (C) 2007 Apple Inc.  All rights reserved.
 * Copyright (C) 2009 Joseph Pecoraro
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1.  Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 * 2.  Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
 *     its contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

import * as Common from '../../core/common/common.js';
import * as Host from '../../core/host/host.js';
import * as i18n from '../../core/i18n/i18n.js';
import * as Platform from '../../core/platform/platform.js';
import * as Root from '../../core/root/root.js';
import * as SDK from '../../core/sdk/sdk.js';
import * as Protocol from '../../generated/protocol.js';
import * as Bindings from '../../models/bindings/bindings.js';
import type * as Formatter from '../../models/formatter/formatter.js';
import * as TextUtils from '../../models/text_utils/text_utils.js';
import * as Workspace from '../../models/workspace/workspace.js';
import * as WorkspaceDiff from '../../models/workspace_diff/workspace_diff.js';
import {formatCSSChangesFromDiff} from '../../panels/utils/utils.js';
import * as DiffView from '../../ui/components/diff_view/diff_view.js';
import * as IconButton from '../../ui/components/icon_button/icon_button.js';
import * as InlineEditor from '../../ui/legacy/components/inline_editor/inline_editor.js';
import * as Components from '../../ui/legacy/components/utils/utils.js';
import * as UI from '../../ui/legacy/legacy.js';

import * as ElementsComponents from './components/components.js';

import {ComputedStyleModel, type ComputedStyleChangedEvent} from './ComputedStyleModel.js';
import {ElementsPanel} from './ElementsPanel.js';
import {ElementsSidebarPane} from './ElementsSidebarPane.js';
import {ImagePreviewPopover} from './ImagePreviewPopover.js';
import {StyleEditorWidget} from './StyleEditorWidget.js';
import {StylePropertyHighlighter} from './StylePropertyHighlighter.js';
import stylesSidebarPaneStyles from './stylesSidebarPane.css.js';

import {activeHints, type StylePropertyTreeElement} from './StylePropertyTreeElement.js';
import {
  StylePropertiesSection,
  BlankStylePropertiesSection,
  KeyframePropertiesSection,
  HighlightPseudoStylePropertiesSection,
  TryRuleSection,
} from './StylePropertiesSection.js';

import * as LayersWidget from './LayersWidget.js';
import {assertNotNullOrUndefined} from '../../core/platform/platform.js';

import {WebCustomData} from './WebCustomData.js';

const UIStrings = {
  /**
   *@description No matches element text content in Styles Sidebar Pane of the Elements panel
   */
  noMatchingSelectorOrStyle: 'No matching selector or style',
  /**
  /**
   *@description Text to announce the result of the filter input in the Styles Sidebar Pane of the Elements panel
   */
  visibleSelectors: '{n, plural, =1 {# visible selector listed below} other {# visible selectors listed below}}',
  /**
   *@description Text in Styles Sidebar Pane of the Elements panel
   */
  invalidPropertyValue: 'Invalid property value',
  /**
   *@description Text in Styles Sidebar Pane of the Elements panel
   */
  unknownPropertyName: 'Unknown property name',
  /**
   *@description Text to filter result items
   */
  filter: 'Filter',
  /**
   *@description ARIA accessible name in Styles Sidebar Pane of the Elements panel
   */
  filterStyles: 'Filter Styles',
  /**
   *@description Separator element text content in Styles Sidebar Pane of the Elements panel
   *@example {scrollbar-corner} PH1
   */
  pseudoSElement: 'Pseudo ::{PH1} element',
  /**
   *@description Text of a DOM element in Styles Sidebar Pane of the Elements panel
   */
  inheritedFroms: 'Inherited from ',
  /**
   *@description Text of an inherited psuedo element in Styles Sidebar Pane of the Elements panel
   *@example {highlight} PH1
   */
  inheritedFromSPseudoOf: 'Inherited from ::{PH1} pseudo of ',
  /**
   *@description Title of  in styles sidebar pane of the elements panel
   *@example {Ctrl} PH1
   */
  incrementdecrementWithMousewheelOne:
      'Increment/decrement with mousewheel or up/down keys. {PH1}: R ±1, Shift: G ±1, Alt: B ±1',
  /**
   *@description Title of  in styles sidebar pane of the elements panel
   *@example {Ctrl} PH1
   */
  incrementdecrementWithMousewheelHundred:
      'Increment/decrement with mousewheel or up/down keys. {PH1}: ±100, Shift: ±10, Alt: ±0.1',
  /**
   *@description Announcement string for invalid properties.
   *@example {Invalid property value} PH1
   *@example {font-size} PH2
   *@example {invalidValue} PH3
   */
  invalidString: '{PH1}, property name: {PH2}, property value: {PH3}',
  /**
   *@description Tooltip text that appears when hovering over the largeicon add button in the Styles Sidebar Pane of the Elements panel
   */
  newStyleRule: 'New Style Rule',
  /**
   *@description Text that is announced by the screen reader when the user focuses on an input field for entering the name of a CSS property in the Styles panel
   *@example {margin} PH1
   */
  cssPropertyName: '`CSS` property name: {PH1}',
  /**
   *@description Text that is announced by the screen reader when the user focuses on an input field for entering the value of a CSS property in the Styles panel
   *@example {10px} PH1
   */
  cssPropertyValue: '`CSS` property value: {PH1}',
  /**
   *@description Tooltip text that appears when hovering over the rendering button in the Styles Sidebar Pane of the Elements panel
   */
  toggleRenderingEmulations: 'Toggle common rendering emulations',
  /**
   *@description Rendering emulation option for toggling the automatic dark mode
   */
  automaticDarkMode: 'Automatic dark mode',
  /**
   *@description Tooltip text that appears when hovering over the css changes button in the Styles Sidebar Pane of the Elements panel
   */
  copyAllCSSChanges: 'Copy CSS changes',
  /**
   *@description Tooltip text that appears after clicking on the copy CSS changes button
   */
  copiedToClipboard: 'Copied to clipboard',
  /**
   *@description Text displayed on layer separators in the styles sidebar pane.
   */
  layer: 'Layer',
  /**
   *@description Tooltip text for the link in the sidebar pane layer separators that reveals the layer in the layer tree view.
   */
  clickToRevealLayer: 'Click to reveal layer in layer tree',
  /**
   *@description Text displayed in tooltip that shows specificity information.
   *@example {(0,0,1)} PH1
   */
  specificity: 'Specificity: {PH1}',
};

const str_ = i18n.i18n.registerUIStrings('panels/elements/StylesSidebarPane.ts', UIStrings);
const i18nString = i18n.i18n.getLocalizedString.bind(undefined, str_);

// Number of ms elapsed with no keypresses to determine is the input is finished, to announce results
const FILTER_IDLE_PERIOD = 500;

// Highlightable properties are those that can be hovered in the sidebar to trigger a specific
// highlighting mode on the current element.
const HIGHLIGHTABLE_PROPERTIES = [
  {mode: 'padding', properties: ['padding']},
  {mode: 'border', properties: ['border']},
  {mode: 'margin', properties: ['margin']},
  {mode: 'gap', properties: ['gap', 'grid-gap']},
  {mode: 'column-gap', properties: ['column-gap', 'grid-column-gap']},
  {mode: 'row-gap', properties: ['row-gap', 'grid-row-gap']},
  {mode: 'grid-template-columns', properties: ['grid-template-columns']},
  {mode: 'grid-template-rows', properties: ['grid-template-rows']},
  {mode: 'grid-template-areas', properties: ['grid-areas']},
  {mode: 'justify-content', properties: ['justify-content']},
  {mode: 'align-content', properties: ['align-content']},
  {mode: 'align-items', properties: ['align-items']},
  {mode: 'flexibility', properties: ['flex', 'flex-basis', 'flex-grow', 'flex-shrink']},
];

let stylesSidebarPaneInstance: StylesSidebarPane;

export class StylesSidebarPane extends Common.ObjectWrapper.eventMixin<EventTypes, typeof ElementsSidebarPane>(
    ElementsSidebarPane) {
  private currentToolbarPane: UI.Widget.Widget|null;
  private animatedToolbarPane: UI.Widget.Widget|null;
  private pendingWidget: UI.Widget.Widget|null;
  private pendingWidgetToggle: UI.Toolbar.ToolbarToggle|null;
  private toolbar: UI.Toolbar.Toolbar|null;
  private toolbarPaneElement: HTMLElement;
  private lastFilterChange: number|null;
  private visibleSections: number|null;
  private noMatchesElement: HTMLElement;
  private sectionsContainer: HTMLElement;
  sectionByElement: WeakMap<Node, StylePropertiesSection>;
  private readonly swatchPopoverHelperInternal: InlineEditor.SwatchPopoverHelper.SwatchPopoverHelper;
  readonly linkifier: Components.Linkifier.Linkifier;
  private readonly decorator: StylePropertyHighlighter;
  private lastRevealedProperty: SDK.CSSProperty.CSSProperty|null;
  private userOperation: boolean;
  isEditingStyle: boolean;
  private filterRegexInternal: RegExp|null;
  private isActivePropertyHighlighted: boolean;
  private initialUpdateCompleted: boolean;
  hasMatchedStyles: boolean;
  private sectionBlocks: SectionBlock[];
  private idleCallbackManager: IdleCallbackManager|null;
  private needsForceUpdate: boolean;
  private readonly resizeThrottler: Common.Throttler.Throttler;

  private scrollerElement?: Element;
  private readonly boundOnScroll: (event: Event) => void;

  private readonly imagePreviewPopover: ImagePreviewPopover;
  #webCustomData?: WebCustomData;
  #hintPopoverHelper: UI.PopoverHelper.PopoverHelper;
  #evaluatedCSSVarPopoverHelper: UI.PopoverHelper.PopoverHelper;

  activeCSSAngle: InlineEditor.CSSAngle.CSSAngle|null;
  #urlToChangeTracker: Map<Platform.DevToolsPath.UrlString, ChangeTracker> = new Map();
  #copyChangesButton?: UI.Toolbar.ToolbarButton;
  #updateAbortController?: AbortController;
  #updateComputedStylesAbortController?: AbortController;

  static instance(opts?: {forceNew: boolean}): StylesSidebarPane {
    if (!stylesSidebarPaneInstance || opts?.forceNew) {
      stylesSidebarPaneInstance = new StylesSidebarPane();
    }
    return stylesSidebarPaneInstance;
  }

  private constructor() {
    super(true /* delegatesFocus */);
    this.setMinimumSize(96, 26);
    this.registerCSSFiles([stylesSidebarPaneStyles]);
    Common.Settings.Settings.instance().moduleSetting('colorFormat').addChangeListener(this.update.bind(this));
    Common.Settings.Settings.instance().moduleSetting('textEditorIndent').addChangeListener(this.update.bind(this));

    this.currentToolbarPane = null;
    this.animatedToolbarPane = null;
    this.pendingWidget = null;
    this.pendingWidgetToggle = null;
    this.toolbar = null;
    this.lastFilterChange = null;
    this.visibleSections = null;
    this.toolbarPaneElement = this.createStylesSidebarToolbar();
    this.computedStyleModelInternal = new ComputedStyleModel();

    this.noMatchesElement = this.contentElement.createChild('div', 'gray-info-message hidden');
    this.noMatchesElement.textContent = i18nString(UIStrings.noMatchingSelectorOrStyle);

    this.sectionsContainer = this.contentElement.createChild('div');
    UI.ARIAUtils.markAsList(this.sectionsContainer);
    this.sectionsContainer.addEventListener('keydown', this.sectionsContainerKeyDown.bind(this), false);
    this.sectionsContainer.addEventListener('focusin', this.sectionsContainerFocusChanged.bind(this), false);
    this.sectionsContainer.addEventListener('focusout', this.sectionsContainerFocusChanged.bind(this), false);
    this.sectionByElement = new WeakMap();

    this.swatchPopoverHelperInternal = new InlineEditor.SwatchPopoverHelper.SwatchPopoverHelper();
    this.swatchPopoverHelperInternal.addEventListener(
        InlineEditor.SwatchPopoverHelper.Events.WillShowPopover, this.hideAllPopovers, this);
    this.linkifier = new Components.Linkifier.Linkifier(MAX_LINK_LENGTH, /* useLinkDecorator */ true);
    this.decorator = new StylePropertyHighlighter(this);
    this.lastRevealedProperty = null;
    this.userOperation = false;
    this.isEditingStyle = false;
    this.filterRegexInternal = null;
    this.isActivePropertyHighlighted = false;
    this.initialUpdateCompleted = false;
    this.hasMatchedStyles = false;

    this.contentElement.classList.add('styles-pane');

    this.sectionBlocks = [];
    this.idleCallbackManager = null;
    this.needsForceUpdate = false;
    stylesSidebarPaneInstance = this;
    UI.Context.Context.instance().addFlavorChangeListener(SDK.DOMModel.DOMNode, this.forceUpdate, this);
    this.contentElement.addEventListener('copy', this.clipboardCopy.bind(this));
    this.resizeThrottler = new Common.Throttler.Throttler(100);

    this.boundOnScroll = this.onScroll.bind(this);
    this.imagePreviewPopover = new ImagePreviewPopover(this.contentElement, event => {
      const link = event.composedPath()[0];
      if (link instanceof Element) {
        return link;
      }
      return null;
    }, () => this.node());

    this.activeCSSAngle = null;

    const showDocumentationSetting =
        Common.Settings.Settings.instance().moduleSetting('showCSSPropertyDocumentationOnHover');
    showDocumentationSetting.addChangeListener(event => {
      const metricType = Boolean(event.data) ? Host.UserMetrics.CSSPropertyDocumentation.ToggledOn :
                                               Host.UserMetrics.CSSPropertyDocumentation.ToggledOff;
      Host.userMetrics.cssPropertyDocumentation(metricType);
    });

    this.#hintPopoverHelper = new UI.PopoverHelper.PopoverHelper(this.contentElement, event => {
      const hoveredNode = event.composedPath()[0];
      // This is a workaround to fix hint popover not showing after icon update.
      // Previously our `.hint` element was an icon itself and `composedPath()[0]` was referring to it.
      // However, our `Icon` component now is an element with shadow root and `event.composedPath()[0]`
      // refers to the markup inside shadow root. Though we want a reference to the `.hint` element itself.
      // So we trace back and reach to the possible `.hint` element from inside the shadow root.
      const possibleHintNodeFromHintIcon = event.composedPath()[2];

      if (!hoveredNode || !(hoveredNode instanceof Element)) {
        return null;
      }

      if (possibleHintNodeFromHintIcon instanceof Element && possibleHintNodeFromHintIcon.matches('.hint')) {
        const hint = activeHints.get(possibleHintNodeFromHintIcon);

        if (hint) {
          return {
            box: hoveredNode.boxInWindow(),
            show: async(popover: UI.GlassPane.GlassPane): Promise<boolean> => {
              const popupElement = new ElementsComponents.CSSHintDetailsView.CSSHintDetailsView(hint);
              popover.contentElement.appendChild(popupElement);
              return true;
            },
          };
        }
      }

      if (showDocumentationSetting.get() && hoveredNode.matches('.webkit-css-property')) {
        if (!this.#webCustomData) {
          this.#webCustomData = WebCustomData.create();
        }

        const cssPropertyName = hoveredNode.textContent;
        const cssProperty = cssPropertyName && this.#webCustomData.findCssProperty(cssPropertyName);

        if (cssProperty) {
          return {
            box: hoveredNode.boxInWindow(),
            show: async(popover: UI.GlassPane.GlassPane): Promise<boolean> => {
              const popupElement = new ElementsComponents.CSSPropertyDocsView.CSSPropertyDocsView(cssProperty);
              popover.contentElement.appendChild(popupElement);
              Host.userMetrics.cssPropertyDocumentation(Host.UserMetrics.CSSPropertyDocumentation.Shown);
              return true;
            },
          };
        }
      }

      if (hoveredNode.matches('.nesting-symbol')) {
        return {
          box: hoveredNode.boxInWindow(),
          show: async(popover: UI.GlassPane.GlassPane): Promise<boolean> => {
            popover.setIgnoreLeftMargin(true);
            const element = document.createElement('span');
            element.textContent = (hoveredNode as HTMLElement).dataset.nestingSelectors || '';
            popover.contentElement.appendChild(element);
            return true;
          },
        };
      }

      if (hoveredNode.matches('.simple-selector')) {
        const specificity = StylePropertiesSection.getSpecificityStoredForNodeElement(hoveredNode);
        return {
          box: hoveredNode.boxInWindow(),
          show: async(popover: UI.GlassPane.GlassPane): Promise<boolean> => {
            popover.setIgnoreLeftMargin(true);
            const element = document.createElement('span');
            element.textContent = i18nString(
                UIStrings.specificity,
                {PH1: specificity ? `(${specificity.a},${specificity.b},${specificity.c})` : '(?,?,?)'});
            popover.contentElement.appendChild(element);
            return true;
          },
        };
      }

      return null;
    });

    this.#hintPopoverHelper.setDisableOnClick(true);
    this.#hintPopoverHelper.setTimeout(300);
    this.#hintPopoverHelper.setHasPadding(true);

    // Bind cssVarSwatch Popover.
    this.#evaluatedCSSVarPopoverHelper = new UI.PopoverHelper.PopoverHelper(this.contentElement, event => {
      const link = event.composedPath()[0];
      if (!link || !(link instanceof Element) || !link.matches('.link-swatch-link')) {
        return null;
      }

      const linkContainer = event.composedPath()[2];
      if (!linkContainer || !(linkContainer instanceof Element) || !linkContainer.matches('.css-var-link')) {
        return null;
      }

      const variableValue = link.getAttribute('data-title') || '';

      return {
        box: link.boxInWindow(),
        show: async(popover: UI.GlassPane.GlassPane): Promise<boolean> => {
          const popupElement = new ElementsComponents.CSSVariableValueView.CSSVariableValueView(variableValue);
          popover.contentElement.appendChild(popupElement);
          return true;
        },
      };
    });
    this.#evaluatedCSSVarPopoverHelper.setDisableOnClick(true);
    this.#evaluatedCSSVarPopoverHelper.setTimeout(500, 200);
  }

  private onScroll(_event: Event): void {
    this.hideAllPopovers();
  }

  swatchPopoverHelper(): InlineEditor.SwatchPopoverHelper.SwatchPopoverHelper {
    return this.swatchPopoverHelperInternal;
  }

  setUserOperation(userOperation: boolean): void {
    this.userOperation = userOperation;
  }

  static createExclamationMark(property: SDK.CSSProperty.CSSProperty, title: string|null): Element {
    const exclamationElement = (document.createElement('span', {is: 'dt-icon-label'}) as UI.UIUtils.DevToolsIconLabel);
    exclamationElement.className = 'exclamation-mark';
    if (!StylesSidebarPane.ignoreErrorsForProperty(property)) {
      exclamationElement
          .data = {iconName: 'warning-filled', color: 'var(--icon-warning)', width: '14px', height: '14px'};
    }
    let invalidMessage: string|Common.UIString.LocalizedString;
    if (title) {
      UI.Tooltip.Tooltip.install(exclamationElement, title);
      invalidMessage = title;
    } else {
      invalidMessage = SDK.CSSMetadata.cssMetadata().isCSSPropertyName(property.name) ?
          i18nString(UIStrings.invalidPropertyValue) :
          i18nString(UIStrings.unknownPropertyName);
      UI.Tooltip.Tooltip.install(exclamationElement, invalidMessage);
    }
    const invalidString =
        i18nString(UIStrings.invalidString, {PH1: invalidMessage, PH2: property.name, PH3: property.value});

    // Storing the invalidString for future screen reader support when editing the property
    property.setDisplayedStringForInvalidProperty(invalidString);

    return exclamationElement;
  }

  static ignoreErrorsForProperty(property: SDK.CSSProperty.CSSProperty): boolean {
    function hasUnknownVendorPrefix(string: string): boolean {
      return !string.startsWith('-webkit-') && /^[-_][\w\d]+-\w/.test(string);
    }

    const name = property.name.toLowerCase();

    // IE hack.
    if (name.charAt(0) === '_') {
      return true;
    }

    // IE has a different format for this.
    if (name === 'filter') {
      return true;
    }

    // Common IE-specific property prefix.
    if (name.startsWith('scrollbar-')) {
      return true;
    }
    if (hasUnknownVendorPrefix(name)) {
      return true;
    }

    const value = property.value.toLowerCase();

    // IE hack.
    if (value.endsWith('\\9')) {
      return true;
    }
    if (hasUnknownVendorPrefix(value)) {
      return true;
    }

    return false;
  }

  static createPropertyFilterElement(
      placeholder: string, container: Element, filterCallback: (arg0: RegExp|null) => void): Element {
    const input = document.createElement('input');
    input.type = 'search';
    input.classList.add('custom-search-input');
    input.placeholder = placeholder;

    function searchHandler(): void {
      const regex = input.value ? new RegExp(Platform.StringUtilities.escapeForRegExp(input.value), 'i') : null;
      filterCallback(regex);
    }
    input.addEventListener('input', searchHandler, false);

    function keydownHandler(event: Event): void {
      const keyboardEvent = (event as KeyboardEvent);
      if (keyboardEvent.key !== Platform.KeyboardUtilities.ESCAPE_KEY || !input.value) {
        return;
      }
      keyboardEvent.consume(true);
      input.value = '';
      searchHandler();
    }
    input.addEventListener('keydown', keydownHandler, false);
    return input;
  }

  static formatLeadingProperties(section: StylePropertiesSection): {
    allDeclarationText: string,
    ruleText: string,
  } {
    const selectorText = section.headerText();
    const indent = Common.Settings.Settings.instance().moduleSetting('textEditorIndent').get();

    const style = section.style();
    const lines: string[] = [];

    // Invalid property should also be copied.
    // For example: *display: inline.
    for (const property of style.leadingProperties()) {
      if (property.disabled) {
        lines.push(`${indent}/* ${property.name}: ${property.value}; */`);
      } else {
        lines.push(`${indent}${property.name}: ${property.value};`);
      }
    }

    const allDeclarationText: string = lines.join('\n');
    const ruleText: string = `${selectorText} {\n${allDeclarationText}\n}`;

    return {
      allDeclarationText,
      ruleText,
    };
  }

  revealProperty(cssProperty: SDK.CSSProperty.CSSProperty): void {
    this.decorator.highlightProperty(cssProperty);
    this.lastRevealedProperty = cssProperty;
    this.update();
  }

  jumpToProperty(propertyName: string): void {
    this.decorator.findAndHighlightPropertyName(propertyName);
  }

  jumpToSectionBlock(section: string): void {
    this.decorator.findAndHighlightSectionBlock(section);
  }

  forceUpdate(): void {
    this.needsForceUpdate = true;
    this.swatchPopoverHelperInternal.hide();
    this.#updateAbortController?.abort();
    this.resetCache();
    this.update();
  }

  private sectionsContainerKeyDown(event: Event): void {
    const activeElement = Platform.DOMUtilities.deepActiveElement(this.sectionsContainer.ownerDocument);
    if (!activeElement) {
      return;
    }
    const section = this.sectionByElement.get(activeElement);
    if (!section) {
      return;
    }
    let sectionToFocus: (StylePropertiesSection|null)|null = null;
    let willIterateForward = false;
    switch ((event as KeyboardEvent).key) {
      case 'ArrowUp':
      case 'ArrowLeft': {
        sectionToFocus = section.previousSibling() || section.lastSibling();
        willIterateForward = false;
        break;
      }
      case 'ArrowDown':
      case 'ArrowRight': {
        sectionToFocus = section.nextSibling() || section.firstSibling();
        willIterateForward = true;
        break;
      }
      case 'Home': {
        sectionToFocus = section.firstSibling();
        willIterateForward = true;
        break;
      }
      case 'End': {
        sectionToFocus = section.lastSibling();
        willIterateForward = false;
        break;
      }
    }

    if (sectionToFocus && this.filterRegexInternal) {
      sectionToFocus = sectionToFocus.findCurrentOrNextVisible(/* willIterateForward= */ willIterateForward);
    }
    if (sectionToFocus) {
      sectionToFocus.element.focus();
      event.consume(true);
    }
  }

  private sectionsContainerFocusChanged(): void {
    this.resetFocus();
  }

  resetFocus(): void {
    // When a styles section is focused, shift+tab should leave the section.
    // Leaving tabIndex = 0 on the first element would cause it to be focused instead.
    if (!this.noMatchesElement.classList.contains('hidden')) {
      return;
    }
    if (this.sectionBlocks[0] && this.sectionBlocks[0].sections[0]) {
      const firstVisibleSection =
          this.sectionBlocks[0].sections[0].findCurrentOrNextVisible(/* willIterateForward= */ true);
      if (firstVisibleSection) {
        firstVisibleSection.element.tabIndex = this.sectionsContainer.hasFocus() ? -1 : 0;
      }
    }
  }

  onAddButtonLongClick(event: Event): void {
    const cssModel = this.cssModel();
    if (!cssModel) {
      return;
    }
    const headers = cssModel.styleSheetHeaders().filter(styleSheetResourceHeader);

    const contextMenuDescriptors: {
      text: string,
      handler: () => Promise<void>,
    }[] = [];
    for (let i = 0; i < headers.length; ++i) {
      const header = headers[i];
      const handler = this.createNewRuleInStyleSheet.bind(this, header);
      contextMenuDescriptors.push({text: Bindings.ResourceUtils.displayNameForURL(header.resourceURL()), handler});
    }

    contextMenuDescriptors.sort(compareDescriptors);

    const contextMenu = new UI.ContextMenu.ContextMenu(event);
    for (let i = 0; i < contextMenuDescriptors.length; ++i) {
      const descriptor = contextMenuDescriptors[i];
      contextMenu.defaultSection().appendItem(descriptor.text, descriptor.handler);
    }
    contextMenu.footerSection().appendItem(
        'inspector-stylesheet', this.createNewRuleInViaInspectorStyleSheet.bind(this));
    void contextMenu.show();

    function compareDescriptors(
        descriptor1: {
          text: string,
          handler: () => Promise<void>,
        },
        descriptor2: {
          text: string,
          handler: () => Promise<void>,
        }): number {
      return Platform.StringUtilities.naturalOrderComparator(descriptor1.text, descriptor2.text);
    }

    function styleSheetResourceHeader(header: SDK.CSSStyleSheetHeader.CSSStyleSheetHeader): boolean {
      return !header.isViaInspector() && !header.isInline && Boolean(header.resourceURL());
    }
  }

  private onFilterChanged(regex: RegExp|null): void {
    this.lastFilterChange = Date.now();
    this.filterRegexInternal = regex;
    this.updateFilter();
    this.resetFocus();
    setTimeout(() => {
      if (this.lastFilterChange) {
        const stillTyping = Date.now() - this.lastFilterChange < FILTER_IDLE_PERIOD;
        if (!stillTyping) {
          UI.ARIAUtils.alert(
              this.visibleSections ? i18nString(UIStrings.visibleSelectors, {n: this.visibleSections}) :
                                     i18nString(UIStrings.noMatchingSelectorOrStyle));
        }
      }
    }, FILTER_IDLE_PERIOD);
  }

  refreshUpdate(editedSection: StylePropertiesSection, editedTreeElement?: StylePropertyTreeElement): void {
    if (editedTreeElement) {
      for (const section of this.allSections()) {
        if (section instanceof BlankStylePropertiesSection && section.isBlank) {
          continue;
        }
        section.updateVarFunctions(editedTreeElement);
      }
    }

    if (this.isEditingStyle) {
      return;
    }
    const node = this.node();
    if (!node) {
      return;
    }

    for (const section of this.allSections()) {
      if (section instanceof BlankStylePropertiesSection && section.isBlank) {
        continue;
      }
      section.update(section === editedSection);
    }

    if (this.filterRegexInternal) {
      this.updateFilter();
    }
    this.swatchPopoverHelper().reposition();
    this.nodeStylesUpdatedForTest(node, false);
  }

  override async doUpdate(): Promise<void> {
    this.#updateAbortController?.abort();
    this.#updateAbortController = new AbortController();
    await this.#innerDoUpdate(this.#updateAbortController.signal);

    // Hide all popovers when scrolling.
    // Styles and Computed panels both have popover (e.g. imagePreviewPopover),
    // so we need to bind both scroll events.
    const scrollerElementLists =
        this?.contentElement?.enclosingNodeOrSelfWithClass('style-panes-wrapper')
            ?.parentElement?.querySelectorAll('.style-panes-wrapper') as unknown as NodeListOf<Element>;
    if (scrollerElementLists.length > 0) {
      for (const element of scrollerElementLists) {
        this.scrollerElement = element;
        this.scrollerElement.addEventListener('scroll', this.boundOnScroll, false);
      }
    }
  }

  async #innerDoUpdate(signal: AbortSignal): Promise<void> {
    if (!this.initialUpdateCompleted) {
      window.setTimeout(() => {
        if (signal.aborted) {
          return;
        }
        if (!this.initialUpdateCompleted) {
          // the spinner will get automatically removed when innerRebuildUpdate is called
          this.sectionsContainer.createChild('span', 'spinner');
        }
      }, 200 /* only spin for loading time > 200ms to avoid unpleasant render flashes */);
    }

    const matchedStyles = await this.fetchMatchedCascade();

    if (signal.aborted) {
      return;
    }

    const nodeId = this.node()?.id;
    const parentNodeId = matchedStyles?.getParentLayoutNodeId();

    const [computedStyles, parentsComputedStyles] =
        await Promise.all([this.fetchComputedStylesFor(nodeId), this.fetchComputedStylesFor(parentNodeId)]);

    if (signal.aborted) {
      return;
    }

    await this.innerRebuildUpdate(signal, matchedStyles, computedStyles, parentsComputedStyles);

    if (signal.aborted) {
      return;
    }

    if (!this.initialUpdateCompleted) {
      this.initialUpdateCompleted = true;
      this.appendToolbarItem(this.createRenderingShortcuts());
      if (Root.Runtime.experiments.isEnabled(Root.Runtime.ExperimentName.STYLES_PANE_CSS_CHANGES)) {
        this.#copyChangesButton = this.createCopyAllChangesButton();
        this.appendToolbarItem(this.#copyChangesButton);
        this.#copyChangesButton.element.classList.add('hidden');
      }
      this.dispatchEventToListeners(Events.InitialUpdateCompleted);
    }

    this.nodeStylesUpdatedForTest((this.node() as SDK.DOMModel.DOMNode), true);

    this.dispatchEventToListeners(Events.StylesUpdateCompleted, {hasMatchedStyles: this.hasMatchedStyles});
  }

  private async fetchComputedStylesFor(nodeId: Protocol.DOM.NodeId|undefined): Promise<Map<string, string>|null> {
    const node = this.node();
    if (node === null || nodeId === undefined) {
      return null;
    }
    return await node.domModel().cssModel().getComputedStyle(nodeId);
  }

  override onResize(): void {
    void this.resizeThrottler.schedule(this.innerResize.bind(this));
  }

  private innerResize(): Promise<void> {
    const width = this.contentElement.getBoundingClientRect().width + 'px';
    this.allSections().forEach(section => {
      section.propertiesTreeOutline.element.style.width = width;
    });
    this.hideAllPopovers();
    return Promise.resolve();
  }

  private resetCache(): void {
    const cssModel = this.cssModel();
    if (cssModel) {
      cssModel.discardCachedMatchedCascade();
    }
  }

  private fetchMatchedCascade(): Promise<SDK.CSSMatchedStyles.CSSMatchedStyles|null> {
    const node = this.node();
    if (!node || !this.cssModel()) {
      return Promise.resolve((null as SDK.CSSMatchedStyles.CSSMatchedStyles | null));
    }

    const cssModel = this.cssModel();
    if (!cssModel) {
      return Promise.resolve(null);
    }
    return cssModel.cachedMatchedCascadeForNode(node).then(validateStyles.bind(this));

    function validateStyles(this: StylesSidebarPane, matchedStyles: SDK.CSSMatchedStyles.CSSMatchedStyles|null):
        SDK.CSSMatchedStyles.CSSMatchedStyles|null {
      return matchedStyles && matchedStyles.node() === this.node() ? matchedStyles : null;
    }
  }

  setEditingStyle(editing: boolean, _treeElement?: StylePropertyTreeElement): void {
    if (this.isEditingStyle === editing) {
      return;
    }
    this.contentElement.classList.toggle('is-editing-style', editing);
    this.isEditingStyle = editing;
    this.setActiveProperty(null);
  }

  setActiveProperty(treeElement: StylePropertyTreeElement|null): void {
    if (this.isActivePropertyHighlighted) {
      SDK.OverlayModel.OverlayModel.hideDOMNodeHighlight();
    }
    this.isActivePropertyHighlighted = false;

    if (!this.node()) {
      return;
    }

    if (!treeElement || treeElement.overloaded() || treeElement.inherited()) {
      return;
    }

    const rule = treeElement.property.ownerStyle.parentRule;
    const selectorList = (rule instanceof SDK.CSSRule.CSSStyleRule) ? rule.selectorText() : undefined;
    for (const {properties, mode} of HIGHLIGHTABLE_PROPERTIES) {
      if (!properties.includes(treeElement.name)) {
        continue;
      }
      const node = this.node();
      if (!node) {
        continue;
      }
      node.domModel().overlayModel().highlightInOverlay(
          {node: (this.node() as SDK.DOMModel.DOMNode), selectorList}, mode);
      this.isActivePropertyHighlighted = true;
      break;
    }
  }

  override onCSSModelChanged(event: Common.EventTarget.EventTargetEvent<ComputedStyleChangedEvent>): void {
    const edit = event?.data && 'edit' in event.data ? event.data.edit : null;
    if (edit) {
      for (const section of this.allSections()) {
        section.styleSheetEdited(edit);
      }
      void this.refreshComputedStyles();
      return;
    }

    if (this.userOperation || this.isEditingStyle) {
      void this.refreshComputedStyles();
      return;
    }

    this.resetCache();
    this.update();
  }

  async refreshComputedStyles(): Promise<void> {
    this.#updateComputedStylesAbortController?.abort();
    this.#updateAbortController = new AbortController();
    const signal = this.#updateAbortController.signal;
    const matchedStyles = await this.fetchMatchedCascade();
    const nodeId = this.node()?.id;
    const parentNodeId = matchedStyles?.getParentLayoutNodeId();

    const [computedStyles, parentsComputedStyles] =
        await Promise.all([this.fetchComputedStylesFor(nodeId), this.fetchComputedStylesFor(parentNodeId)]);

    if (signal.aborted) {
      return;
    }

    for (const section of this.allSections()) {
      section.setComputedStyles(computedStyles);
      section.setParentsComputedStyles(parentsComputedStyles);
      section.updateAuthoringHint();
    }
  }

  focusedSectionIndex(): number {
    let index = 0;
    for (const block of this.sectionBlocks) {
      for (const section of block.sections) {
        if (section.element.hasFocus()) {
          return index;
        }
        index++;
      }
    }
    return -1;
  }

  continueEditingElement(sectionIndex: number, propertyIndex: number): void {
    const section = this.allSections()[sectionIndex];
    if (section) {
      const element = (section.closestPropertyForEditing(propertyIndex) as StylePropertyTreeElement | null);
      if (!element) {
        section.element.focus();
        return;
      }
      element.startEditing();
    }
  }

  private async innerRebuildUpdate(
      signal: AbortSignal, matchedStyles: SDK.CSSMatchedStyles.CSSMatchedStyles|null,
      computedStyles: Map<string, string>|null, parentsComputedStyles: Map<string, string>|null): Promise<void> {
    // ElementsSidebarPane's throttler schedules this method. Usually,
    // rebuild is suppressed while editing (see onCSSModelChanged()), but we need a
    // 'force' flag since the currently running throttler process cannot be canceled.
    if (this.needsForceUpdate) {
      this.needsForceUpdate = false;
    } else if (this.isEditingStyle || this.userOperation) {
      return;
    }

    const focusedIndex = this.focusedSectionIndex();

    this.linkifier.reset();
    const prevSections = this.sectionBlocks.map(block => block.sections).flat();
    this.sectionBlocks = [];

    const node = this.node();
    this.hasMatchedStyles = matchedStyles !== null && node !== null;
    if (!this.hasMatchedStyles) {
      this.sectionsContainer.removeChildren();
      this.noMatchesElement.classList.remove('hidden');
      return;
    }

    const blocks = await this.rebuildSectionsForMatchedStyleRules(
        (matchedStyles as SDK.CSSMatchedStyles.CSSMatchedStyles), computedStyles, parentsComputedStyles);

    if (signal.aborted) {
      return;
    }

    this.sectionBlocks = blocks;

    // Style sections maybe re-created when flexbox editor is activated.
    // With the following code we re-bind the flexbox editor to the new
    // section with the same index as the previous section had.
    const newSections = this.sectionBlocks.map(block => block.sections).flat();
    const styleEditorWidget = StyleEditorWidget.instance();
    const boundSection = styleEditorWidget.getSection();
    if (boundSection) {
      styleEditorWidget.unbindContext();
      for (const [index, prevSection] of prevSections.entries()) {
        if (boundSection === prevSection && index < newSections.length) {
          styleEditorWidget.bindContext(this, newSections[index]);
        }
      }
    }

    this.sectionsContainer.removeChildren();
    const fragment = document.createDocumentFragment();

    let index = 0;
    let elementToFocus: HTMLDivElement|null = null;
    for (const block of this.sectionBlocks) {
      const titleElement = block.titleElement();
      if (titleElement) {
        fragment.appendChild(titleElement);
      }
      for (const section of block.sections) {
        fragment.appendChild(section.element);
        if (index === focusedIndex) {
          elementToFocus = section.element;
        }
        index++;
      }
    }

    this.sectionsContainer.appendChild(fragment);

    if (elementToFocus) {
      elementToFocus.focus();
    }

    if (focusedIndex >= index) {
      this.sectionBlocks[0].sections[0].element.focus();
    }

    this.sectionsContainerFocusChanged();

    if (this.filterRegexInternal) {
      this.updateFilter();
    } else {
      this.noMatchesElement.classList.toggle('hidden', this.sectionBlocks.length > 0);
    }
    if (this.lastRevealedProperty) {
      this.decorator.highlightProperty(this.lastRevealedProperty);
      this.lastRevealedProperty = null;
    }

    this.swatchPopoverHelper().reposition();

    // Record the elements tool load time after the sidepane has loaded.
    Host.userMetrics.panelLoaded('elements', 'DevTools.Launch.Elements');

    this.dispatchEventToListeners(Events.StylesUpdateCompleted, {hasMatchedStyles: false});
  }

  private nodeStylesUpdatedForTest(_node: SDK.DOMModel.DOMNode, _rebuild: boolean): void {
    // For sniffing in tests.
  }

  rebuildSectionsForMatchedStyleRulesForTest(
      matchedStyles: SDK.CSSMatchedStyles.CSSMatchedStyles, computedStyles: Map<string, string>|null,
      parentsComputedStyles: Map<string, string>|null): Promise<SectionBlock[]> {
    return this.rebuildSectionsForMatchedStyleRules(matchedStyles, computedStyles, parentsComputedStyles);
  }

  private async rebuildSectionsForMatchedStyleRules(
      matchedStyles: SDK.CSSMatchedStyles.CSSMatchedStyles, computedStyles: Map<string, string>|null,
      parentsComputedStyles: Map<string, string>|null): Promise<SectionBlock[]> {
    if (this.idleCallbackManager) {
      this.idleCallbackManager.discard();
    }

    this.idleCallbackManager = new IdleCallbackManager();

    const blocks = [new SectionBlock(null)];
    let sectionIdx = 0;
    let lastParentNode: SDK.DOMModel.DOMNode|null = null;

    let lastLayers: SDK.CSSLayer.CSSLayer[]|null = null;
    let sawLayers: boolean = false;

    const addLayerSeparator = (style: SDK.CSSStyleDeclaration.CSSStyleDeclaration): void => {
      const parentRule = style.parentRule;
      if (parentRule instanceof SDK.CSSRule.CSSStyleRule) {
        const layers = parentRule.layers;
        if ((layers.length || lastLayers) && lastLayers !== layers) {
          const block = SectionBlock.createLayerBlock(parentRule);
          blocks.push(block);
          sawLayers = true;
          lastLayers = layers;
        }
      }
    };

    // We disable the layer widget initially. If we see a layer in
    // the matched styles we reenable the button.
    LayersWidget.ButtonProvider.instance().item().setVisible(false);

    const refreshedURLs = new Set<string>();
    for (const style of matchedStyles.nodeStyles()) {
      if (Root.Runtime.experiments.isEnabled(Root.Runtime.ExperimentName.STYLES_PANE_CSS_CHANGES) && style.parentRule) {
        const url = style.parentRule.resourceURL();
        if (url && !refreshedURLs.has(url)) {
          await this.trackURLForChanges(url);
          refreshedURLs.add(url);
        }
      }

      const parentNode = matchedStyles.isInherited(style) ? matchedStyles.nodeForStyle(style) : null;
      if (parentNode && parentNode !== lastParentNode) {
        lastParentNode = parentNode;
        const block = await SectionBlock.createInheritedNodeBlock(lastParentNode);
        blocks.push(block);
      }

      addLayerSeparator(style);

      const lastBlock = blocks[blocks.length - 1];
      if (lastBlock) {
        this.idleCallbackManager.schedule(() => {
          const section =
              new StylePropertiesSection(this, matchedStyles, style, sectionIdx, computedStyles, parentsComputedStyles);
          sectionIdx++;
          lastBlock.sections.push(section);
        });
      }
    }

    const customHighlightPseudoRulesets: {
      highlightName: string|null,
      pseudoType: Protocol.DOM.PseudoType,
      pseudoStyles: SDK.CSSStyleDeclaration.CSSStyleDeclaration[],
    }[] = Array.from(matchedStyles.customHighlightPseudoNames()).map(highlightName => {
      return {
        'highlightName': highlightName,
        'pseudoType': Protocol.DOM.PseudoType.Highlight,
        'pseudoStyles': matchedStyles.customHighlightPseudoStyles(highlightName),
      };
    });

    const otherPseudoRulesets: {
      highlightName: string|null,
      pseudoType: Protocol.DOM.PseudoType,
      pseudoStyles: SDK.CSSStyleDeclaration.CSSStyleDeclaration[],
    }[] = [...matchedStyles.pseudoTypes()].map(pseudoType => {
      return {'highlightName': null, 'pseudoType': pseudoType, 'pseudoStyles': matchedStyles.pseudoStyles(pseudoType)};
    });

    const pseudoRulesets = customHighlightPseudoRulesets.concat(otherPseudoRulesets).sort((a, b) => {
      // We want to show the ::before pseudos first, followed by the remaining pseudos
      // in alphabetical order.
      if (a.pseudoType === Protocol.DOM.PseudoType.Before && b.pseudoType !== Protocol.DOM.PseudoType.Before) {
        return -1;
      }
      if (a.pseudoType !== Protocol.DOM.PseudoType.Before && b.pseudoType === Protocol.DOM.PseudoType.Before) {
        return 1;
      }
      if (a.pseudoType < b.pseudoType) {
        return -1;
      }
      if (a.pseudoType > b.pseudoType) {
        return 1;
      }
      return 0;
    });

    for (const pseudo of pseudoRulesets) {
      lastParentNode = null;
      for (let i = 0; i < pseudo.pseudoStyles.length; ++i) {
        const style = pseudo.pseudoStyles[i];
        const parentNode = matchedStyles.isInherited(style) ? matchedStyles.nodeForStyle(style) : null;

        // Start a new SectionBlock if this is the first rule for this pseudo type, or if this
        // rule is inherited from a different parent than the previous rule.
        if (i === 0 || parentNode !== lastParentNode) {
          lastLayers = null;
          if (parentNode) {
            const block =
                await SectionBlock.createInheritedPseudoTypeBlock(pseudo.pseudoType, pseudo.highlightName, parentNode);
            blocks.push(block);
          } else {
            const block = SectionBlock.createPseudoTypeBlock(pseudo.pseudoType, pseudo.highlightName);
            blocks.push(block);
          }
        }
        lastParentNode = parentNode;

        addLayerSeparator(style);
        const lastBlock = blocks[blocks.length - 1];
        this.idleCallbackManager.schedule(() => {
          const section = new HighlightPseudoStylePropertiesSection(
              this, matchedStyles, style, sectionIdx, computedStyles, parentsComputedStyles);
          sectionIdx++;
          lastBlock.sections.push(section);
        });
      }
    }

    for (const keyframesRule of matchedStyles.keyframes()) {
      const block = SectionBlock.createKeyframesBlock(keyframesRule.name().text);
      for (const keyframe of keyframesRule.keyframes()) {
        this.idleCallbackManager.schedule(() => {
          block.sections.push(new KeyframePropertiesSection(this, matchedStyles, keyframe.style, sectionIdx));
          sectionIdx++;
        });
      }
      blocks.push(block);
    }

    for (const positionFallbackRule of matchedStyles.positionFallbackRules()) {
      const block = SectionBlock.createPositionFallbackBlock(positionFallbackRule.name().text);
      for (const tryRule of positionFallbackRule.tryRules()) {
        this.idleCallbackManager.schedule(() => {
          block.sections.push(new TryRuleSection(
              this, matchedStyles, tryRule.style, sectionIdx, computedStyles, parentsComputedStyles));
          sectionIdx++;
        });
      }
      blocks.push(block);
    }

    // If we have seen a layer in matched styles we enable
    // the layer widget button.
    if (sawLayers) {
      LayersWidget.ButtonProvider.instance().item().setVisible(true);
    } else if (LayersWidget.LayersWidget.instance().isShowing()) {
      // Since the button for toggling the layers view is now hidden
      // we ensure that the layers view is not currently toggled.
      ElementsPanel.instance().showToolbarPane(null, LayersWidget.ButtonProvider.instance().item());
    }

    await this.idleCallbackManager.awaitDone();

    return blocks;
  }

  async createNewRuleInViaInspectorStyleSheet(): Promise<void> {
    const cssModel = this.cssModel();
    const node = this.node();
    if (!cssModel || !node) {
      return;
    }
    this.setUserOperation(true);

    const styleSheetHeader = await cssModel.requestViaInspectorStylesheet((node as SDK.DOMModel.DOMNode));

    this.setUserOperation(false);
    await this.createNewRuleInStyleSheet(styleSheetHeader);
  }

  private async createNewRuleInStyleSheet(styleSheetHeader: SDK.CSSStyleSheetHeader.CSSStyleSheetHeader|
                                          null): Promise<void> {
    if (!styleSheetHeader) {
      return;
    }

    const text = (await styleSheetHeader.requestContent()).content || '';
    const lines = text.split('\n');
    const range = TextUtils.TextRange.TextRange.createFromLocation(lines.length - 1, lines[lines.length - 1].length);

    if (this.sectionBlocks && this.sectionBlocks.length > 0) {
      this.addBlankSection(this.sectionBlocks[0].sections[0], styleSheetHeader.id, range);
    }
  }

  addBlankSection(
      insertAfterSection: StylePropertiesSection, styleSheetId: Protocol.CSS.StyleSheetId,
      ruleLocation: TextUtils.TextRange.TextRange): void {
    const node = this.node();
    const blankSection = new BlankStylePropertiesSection(
        this, insertAfterSection.matchedStyles, node ? node.simpleSelector() : '', styleSheetId, ruleLocation,
        insertAfterSection.style(), 0);

    this.sectionsContainer.insertBefore(blankSection.element, insertAfterSection.element.nextSibling);

    for (const block of this.sectionBlocks) {
      const index = block.sections.indexOf(insertAfterSection);
      if (index === -1) {
        continue;
      }
      block.sections.splice(index + 1, 0, blankSection);
      blankSection.startEditingSelector();
    }
    let sectionIdx = 0;
    for (const block of this.sectionBlocks) {
      for (const section of block.sections) {
        section.setSectionIdx(sectionIdx);
        sectionIdx++;
      }
    }
  }

  removeSection(section: StylePropertiesSection): void {
    for (const block of this.sectionBlocks) {
      const index = block.sections.indexOf(section);
      if (index === -1) {
        continue;
      }
      block.sections.splice(index, 1);
      section.element.remove();
    }
  }

  filterRegex(): RegExp|null {
    return this.filterRegexInternal;
  }

  private updateFilter(): void {
    let hasAnyVi