diff --git a/src/vs/workbench/browser/parts/auxiliarybar/auxiliaryBarPart.ts b/src/vs/workbench/browser/parts/auxiliarybar/auxiliaryBarPart.ts
index 742969265714c0ad53f1569a9c8e678a8fa17878..006c388becca45e32cd89141ade8eb8f39a9f471 100644
--- a/src/vs/workbench/browser/parts/auxiliarybar/auxiliaryBarPart.ts
+++ b/src/vs/workbench/browser/parts/auxiliarybar/auxiliaryBarPart.ts
@@ -12,19 +12,20 @@ import { IKeybindingService } from 'vs/platform/keybinding/common/keybinding';
 import { INotificationService } from 'vs/platform/notification/common/notification';
 import { IStorageService } from 'vs/platform/storage/common/storage';
 import { ITelemetryService } from 'vs/platform/telemetry/common/telemetry';
-import { activeContrastBorder, editorBackground, focusBorder } from 'vs/platform/theme/common/colorRegistry';
+import { activeContrastBorder, contrastBorder, editorBackground, focusBorder } from 'vs/platform/theme/common/colorRegistry';
 import { IThemeService, registerThemingParticipant } from 'vs/platform/theme/common/themeService';
 import { Extensions as PaneCompositeExtensions } from 'vs/workbench/browser/panecomposite';
 import { BasePanelPart } from 'vs/workbench/browser/parts/panel/panelPart';
 import { ActiveAuxiliaryContext, AuxiliaryBarFocusContext } from 'vs/workbench/common/auxiliarybar';
-import { SIDE_BAR_BACKGROUND, SIDE_BAR_TITLE_FOREGROUND } from 'vs/workbench/common/theme';
+import { SIDE_BAR_BACKGROUND, SIDE_BAR_BORDER, SIDE_BAR_TITLE_FOREGROUND } from 'vs/workbench/common/theme';
 import { IViewDescriptorService, ViewContainerLocation } from 'vs/workbench/common/views';
 import { IExtensionService } from 'vs/workbench/services/extensions/common/extensions';
-import { IWorkbenchLayoutService, Parts } from 'vs/workbench/services/layout/browser/layoutService';
+import { IWorkbenchLayoutService, Parts, Position } from 'vs/workbench/services/layout/browser/layoutService';
 import { IActivityHoverOptions } from 'vs/workbench/browser/parts/compositeBarActions';
 import { HoverPosition } from 'vs/base/browser/ui/hover/hoverWidget';
 import { IAction, Separator } from 'vs/base/common/actions';
 import { ToggleAuxiliaryBarAction } from 'vs/workbench/browser/parts/auxiliarybar/auxiliaryBarActions';
+import { assertIsDefined } from 'vs/base/common/types';
 
 export class AuxiliaryBarPart extends BasePanelPart {
 	static readonly activePanelSettingsKey = 'workbench.auxiliarybar.activepanelid';
@@ -60,6 +61,7 @@ export class AuxiliaryBarPart extends BasePanelPart {
 			ViewContainerLocation.AuxiliaryBar,
 			ActiveAuxiliaryContext.bindTo(contextKeyService),
 			AuxiliaryBarFocusContext.bindTo(contextKeyService),
+			() => (this.getColor(SIDE_BAR_BORDER) || this.getColor(contrastBorder)) ? 1 : 0,
 			notificationService,
 			storageService,
 			telemetryService,
@@ -74,6 +76,28 @@ export class AuxiliaryBarPart extends BasePanelPart {
 		);
 	}
 
+	// override layout(width: number, height: number, top: number, left: number): void {
+	// 	// Layout contents
+	// 	super.layout(width, height, top, left); // Take into account the 1px border when layouting
+	// }
+
+	override updateStyles(): void {
+		super.updateStyles();
+
+		const container = assertIsDefined(this.getContainer());
+		const borderColor = this.getColor(SIDE_BAR_BORDER) || this.getColor(contrastBorder);
+		const isPositionLeft = this.layoutService.getSideBarPosition() === Position.RIGHT;
+
+		container.style.borderLeftColor = borderColor ?? '';
+		container.style.borderRightColor = borderColor ?? '';
+
+		container.style.borderLeftStyle = borderColor && !isPositionLeft ? 'solid' : 'none';
+		container.style.borderRightStyle = borderColor && isPositionLeft ? 'solid' : 'none';
+
+		container.style.borderLeftWidth = borderColor && !isPositionLeft ? '1px' : '0px';
+		container.style.borderRightWidth = borderColor && isPositionLeft ? '1px' : '0px';
+	}
+
 	protected getActivityHoverOptions(): IActivityHoverOptions {
 		return {
 			position: () => HoverPosition.BELOW
diff --git a/src/vs/workbench/browser/parts/panel/panelPart.ts b/src/vs/workbench/browser/parts/panel/panelPart.ts
index 0b2ff517030fd4072fa83917e458051adbab58e8..2e29a8fca84a2087ddcc49a6bc377b9f75f153eb 100644
--- a/src/vs/workbench/browser/parts/panel/panelPart.ts
+++ b/src/vs/workbench/browser/parts/panel/panelPart.ts
@@ -112,6 +112,7 @@ export abstract class BasePanelPart extends CompositePart<PaneComposite> impleme
 		private readonly viewContainerLocation: ViewContainerLocation,
 		private readonly activePanelContextKey: IContextKey<string>,
 		private panelFocusContextKey: IContextKey<boolean>,
+		borderWidth: (() => number) | undefined,
 		@INotificationService notificationService: INotificationService,
 		@IStorageService storageService: IStorageService,
 		@ITelemetryService telemetryService: ITelemetryService,
@@ -140,7 +141,7 @@ export abstract class BasePanelPart extends CompositePart<PaneComposite> impleme
 			'panel',
 			undefined,
 			partId,
-			{ hasTitle: true }
+			{ hasTitle: true, borderWidth }
 		);
 
 		this.panelRegistry = Registry.as<PaneCompositeRegistry>(panelRegistryId);
@@ -476,13 +477,13 @@ export abstract class BasePanelPart extends CompositePart<PaneComposite> impleme
 
 		const container = assertIsDefined(this.getContainer());
 		container.style.backgroundColor = this.getColor(this.backgroundColor) || '';
-		const borderColor = this.getColor(PANEL_BORDER) || this.getColor(contrastBorder) || '';
+		const borderColor = this.getColor(contrastBorder) || '';
 		container.style.borderLeftColor = borderColor;
 		container.style.borderRightColor = borderColor;
 
 		const title = this.getTitleArea();
 		if (title) {
-			title.style.borderTopColor = this.getColor(PANEL_BORDER) || this.getColor(contrastBorder) || '';
+			title.style.borderTopColor = this.getColor(contrastBorder) || '';
 		}
 	}
 
@@ -840,6 +841,7 @@ export class PanelPart extends BasePanelPart {
 			ViewContainerLocation.Panel,
 			ActivePanelContext.bindTo(contextKeyService),
 			PanelFocusContext.bindTo(contextKeyService),
+			undefined,
 			notificationService,
 			storageService,
 			telemetryService,
@@ -858,6 +860,20 @@ export class PanelPart extends BasePanelPart {
 		this._register(this.globalActions.onDidChange(() => this.updateGlobalToolbarActions()));
 	}
 
+	override updateStyles(): void {
+		super.updateStyles();
+
+		const container = assertIsDefined(this.getContainer());
+		const borderColor = this.getColor(PANEL_BORDER) || this.getColor(contrastBorder) || '';
+		container.style.borderLeftColor = borderColor;
+		container.style.borderRightColor = borderColor;
+
+		const title = this.getTitleArea();
+		if (title) {
+			title.style.borderTopColor = this.getColor(PANEL_BORDER) || this.getColor(contrastBorder) || '';
+		}
+	}
+
 	protected getActivityHoverOptions(): IActivityHoverOptions {
 		return {
 			position: () => this.layoutService.getPanelPosition() === Position.BOTTOM && !this.layoutService.isPanelMaximized() ? HoverPosition.ABOVE : HoverPosition.BELOW,