diff --git a/src/vs/base/browser/dom.ts b/src/vs/base/browser/dom.ts
index 2d753c91e78..7d5f15fc6e6 100644
--- a/src/vs/base/browser/dom.ts
+++ b/src/vs/base/browser/dom.ts
@@ -35,33 +35,17 @@ export function isInDOM(node: Node | null): boolean {
 
 interface IDomClassList {
 	addClass(node: HTMLElement | SVGElement, className: string): void;
-	addClasses(node: HTMLElement | SVGElement, ...classNames: string[]): void;
-	removeClasses(node: HTMLElement | SVGElement, ...classNames: string[]): void;
 	toggleClass(node: HTMLElement | SVGElement, className: string, shouldHaveIt?: boolean): void;
 }
 
 const _classList: IDomClassList = new class implements IDomClassList {
 
-	addClasses(node: HTMLElement, ...classNames: string[]): void {
-		classNames.forEach(nameValue => nameValue.split(' ').forEach(name => this.addClass(node, name)));
-	}
-
 	addClass(node: HTMLElement, className: string): void {
 		if (className && node.classList) {
 			node.classList.add(className);
 		}
 	}
 
-	removeClass(node: HTMLElement, className: string): void {
-		if (className && node.classList) {
-			node.classList.remove(className);
-		}
-	}
-
-	removeClasses(node: HTMLElement, ...classNames: string[]): void {
-		classNames.forEach(nameValue => nameValue.split(' ').forEach(name => this.removeClass(node, name)));
-	}
-
 	toggleClass(node: HTMLElement, className: string, shouldHaveIt?: boolean): void {
 		if (node.classList) {
 			node.classList.toggle(className, shouldHaveIt);
@@ -72,10 +56,6 @@ const _classList: IDomClassList = new class implements IDomClassList {
 /** @deprecated ES6 - use classList*/
 export function addClass(node: HTMLElement | SVGElement, className: string): void { return _classList.addClass(node, className); }
 /** @deprecated ES6 - use classList*/
-export function addClasses(node: HTMLElement | SVGElement, ...classNames: string[]): void { return _classList.addClasses(node, ...classNames); }
-/** @deprecated ES6 - use classList*/
-export function removeClasses(node: HTMLElement | SVGElement, ...classNames: string[]): void { return _classList.removeClasses(node, ...classNames); }
-/** @deprecated ES6 - use classList*/
 export function toggleClass(node: HTMLElement | SVGElement, className: string, shouldHaveIt?: boolean): void { return _classList.toggleClass(node, className, shouldHaveIt); }
 
 class DomListener implements IDisposable {
diff --git a/src/vs/editor/contrib/codeAction/lightBulbWidget.ts b/src/vs/editor/contrib/codeAction/lightBulbWidget.ts
index 5caf1cd6a60..2d95a32a5ae 100644
--- a/src/vs/editor/contrib/codeAction/lightBulbWidget.ts
+++ b/src/vs/editor/contrib/codeAction/lightBulbWidget.ts
@@ -204,8 +204,8 @@ export class LightBulbWidget extends Disposable implements IContentWidget {
 	private _updateLightBulbTitleAndIcon(): void {
 		if (this.state.type === LightBulbState.Type.Showing && this.state.actions.hasAutoFix) {
 			// update icon
-			dom.removeClasses(this._domNode, Codicon.lightBulb.classNames);
-			dom.addClasses(this._domNode, Codicon.lightbulbAutofix.classNames);
+			this._domNode.classList.remove(...Codicon.lightBulb.classNamesArray);
+			this._domNode.classList.add(...Codicon.lightbulbAutofix.classNamesArray);
 
 			const preferredKb = this._keybindingService.lookupKeybinding(this._preferredFixActionId);
 			if (preferredKb) {
@@ -215,8 +215,8 @@ export class LightBulbWidget extends Disposable implements IContentWidget {
 		}
 
 		// update icon
-		dom.removeClasses(this._domNode, Codicon.lightbulbAutofix.classNames);
-		dom.addClasses(this._domNode, Codicon.lightBulb.classNames);
+		this._domNode.classList.remove(...Codicon.lightbulbAutofix.classNamesArray);
+		this._domNode.classList.add(...Codicon.lightBulb.classNamesArray);
 
 		const kb = this._keybindingService.lookupKeybinding(this._quickFixActionId);
 		if (kb) {
diff --git a/src/vs/workbench/services/themes/browser/workbenchThemeService.ts b/src/vs/workbench/services/themes/browser/workbenchThemeService.ts
index eb96d29d5cd..cde9e21cf7e 100644
--- a/src/vs/workbench/services/themes/browser/workbenchThemeService.ts
+++ b/src/vs/workbench/services/themes/browser/workbenchThemeService.ts
@@ -18,7 +18,7 @@ import { Event, Emitter } from 'vs/base/common/event';
 import { registerFileIconThemeSchemas } from 'vs/workbench/services/themes/common/fileIconThemeSchema';
 import { IDisposable, dispose } from 'vs/base/common/lifecycle';
 import { FileIconThemeData } from 'vs/workbench/services/themes/browser/fileIconThemeData';
-import { removeClasses, addClasses, createStyleSheet } from 'vs/base/browser/dom';
+import { createStyleSheet } from 'vs/base/browser/dom';
 import { IWorkbenchEnvironmentService } from 'vs/workbench/services/environment/common/environmentService';
 import { IFileService, FileChangeType } from 'vs/platform/files/common/files';
 import { URI } from 'vs/base/common/uri';
@@ -456,11 +456,11 @@ export class WorkbenchThemeService implements IWorkbenchThemeService {
 		this.updateDynamicCSSRules(newTheme);
 
 		if (this.currentColorTheme.id) {
-			removeClasses(this.container, this.currentColorTheme.id);
+			this.container.classList.remove(...this.currentColorTheme.classNames);
 		} else {
-			removeClasses(this.container, VS_DARK_THEME, VS_LIGHT_THEME, VS_HC_THEME);
+			this.container.classList.remove(VS_DARK_THEME, VS_LIGHT_THEME, VS_HC_THEME);
 		}
-		addClasses(this.container, newTheme.id);
+		this.container.classList.add(...newTheme.classNames);
 
 		this.currentColorTheme.clearCaches();
 		this.currentColorTheme = newTheme;
@@ -575,9 +575,9 @@ export class WorkbenchThemeService implements IWorkbenchThemeService {
 		_applyRules(iconThemeData.styleSheetContent!, fileIconThemeRulesClassName);
 
 		if (iconThemeData.id) {
-			addClasses(this.container, fileIconsEnabledClass);
+			this.container.classList.add(fileIconsEnabledClass);
 		} else {
-			removeClasses(this.container, fileIconsEnabledClass);
+			this.container.classList.remove(fileIconsEnabledClass);
 		}
 
 		this.fileIconThemeWatcher.update(iconThemeData);
diff --git a/src/vs/workbench/services/themes/common/colorThemeData.ts b/src/vs/workbench/services/themes/common/colorThemeData.ts
index b4cef7e7368..73ede2fd1f3 100644
--- a/src/vs/workbench/services/themes/common/colorThemeData.ts
+++ b/src/vs/workbench/services/themes/common/colorThemeData.ts
@@ -515,7 +515,6 @@ export class ColorThemeData implements IWorkbenchColorTheme {
 			id: this.id,
 			label: this.label,
 			settingsId: this.settingsId,
-			selector: this.id.split(' ').join('.'), // to not break old clients
 			themeTokenColors: this.themeTokenColors,
 			semanticTokenRules: this.semanticTokenRules.map(SemanticTokenRule.toJSONObject),
 			extensionData: ExtensionData.toJSONObject(this.extensionData),
@@ -527,7 +526,11 @@ export class ColorThemeData implements IWorkbenchColorTheme {
 	}
 
 	get baseTheme(): string {
-		return this.id.split(' ')[0];
+		return this.classNames[0];
+	}
+
+	get classNames(): string[] {
+		return this.id.split(' ');
 	}
 
 	get type(): ColorScheme {