diff --git a/extensions/merge-conflict/src/mergeDecorator.ts b/extensions/merge-conflict/src/mergeDecorator.ts
index 1b419908847af340560c8bde2778f36700757484..d30863eca9ae9ed58b77b2e31f49c15658028c27 100644
--- a/extensions/merge-conflict/src/mergeDecorator.ts
+++ b/extensions/merge-conflict/src/mergeDecorator.ts
@@ -80,6 +80,9 @@ export default class MergeDectorator implements vscode.Disposable {
 				isWholeLine: this.decorationUsesWholeLine,
 				backgroundColor: new vscode.ThemeColor('merge.currentHeaderBackground'),
 				color: new vscode.ThemeColor('editor.foreground'),
+				outlineStyle: 'solid',
+				outlineWidth: '1pt',
+				outlineColor: new vscode.ThemeColor('merge.border'),
 				after: {
 					contentText: ' ' + localize('currentChange', '(Current change)'),
 					color: new vscode.ThemeColor('descriptionForeground')
@@ -88,12 +91,18 @@ export default class MergeDectorator implements vscode.Disposable {
 
 			this.decorations['splitter'] = vscode.window.createTextEditorDecorationType({
 				color: new vscode.ThemeColor('editor.foreground'),
+				outlineStyle: 'solid',
+				outlineWidth: '1pt',
+				outlineColor: new vscode.ThemeColor('merge.border'),
 				isWholeLine: this.decorationUsesWholeLine,
 			});
 
 			this.decorations['incoming.header'] = vscode.window.createTextEditorDecorationType({
 				backgroundColor: new vscode.ThemeColor('merge.incomingHeaderBackground'),
 				color: new vscode.ThemeColor('editor.foreground'),
+				outlineStyle: 'solid',
+				outlineWidth: '1pt',
+				outlineColor: new vscode.ThemeColor('merge.border'),
 				isWholeLine: this.decorationUsesWholeLine,
 				after: {
 					contentText: ' ' + localize('incomingChange', '(Incoming change)'),
diff --git a/src/vs/platform/theme/common/colorRegistry.ts b/src/vs/platform/theme/common/colorRegistry.ts
index ce0e3fd190ba1837c0379203268d1cb44192f452..d790e964b0cf8bd100d0dab3ac85b8dfb54c10de 100644
--- a/src/vs/platform/theme/common/colorRegistry.ts
+++ b/src/vs/platform/theme/common/colorRegistry.ts
@@ -264,13 +264,15 @@ const incomingBaseColor = Color.fromHex('#40A6FF').transparent(headerTransparenc
 const contentTransparency = 0.4;
 const rulerTransparency = 1;
 
-export const mergeCurrentHeaderBackground = registerColor('merge.currentHeaderBackground', { dark: currentBaseColor, light: currentBaseColor, hc: currentBaseColor }, nls.localize('mergeCurrentHeaderBackground', 'Current header background in inline merge-conflict.'));
-export const mergeCurrentContentBackground = registerColor('merge.currentContentBackground', { dark: transparent(mergeCurrentHeaderBackground, contentTransparency), light: transparent(mergeCurrentHeaderBackground, contentTransparency), hc: transparent(mergeCurrentHeaderBackground, contentTransparency) }, nls.localize('mergeCurrentContentBackground', 'Current content background in inline merge-conflict.'));
-export const mergeIncomingHeaderBackground = registerColor('merge.incomingHeaderBackground', { dark: incomingBaseColor, light: incomingBaseColor, hc: incomingBaseColor }, nls.localize('mergeIncomingHeaderBackground', 'Incoming header background in inline merge-conflict.'));
-export const mergeIncomingContentBackground = registerColor('merge.incomingContentBackground', { dark: transparent(mergeIncomingHeaderBackground, contentTransparency), light: transparent(mergeIncomingHeaderBackground, contentTransparency), hc: transparent(mergeIncomingHeaderBackground, contentTransparency) }, nls.localize('mergeIncomingContentBackground', 'Incoming content background in inline merge-conflict.'));
+export const mergeCurrentHeaderBackground = registerColor('merge.currentHeaderBackground', { dark: currentBaseColor, light: currentBaseColor, hc: null }, nls.localize('mergeCurrentHeaderBackground', 'Current header background in inline merge-conflicts.'));
+export const mergeCurrentContentBackground = registerColor('merge.currentContentBackground', { dark: transparent(mergeCurrentHeaderBackground, contentTransparency), light: transparent(mergeCurrentHeaderBackground, contentTransparency), hc: transparent(mergeCurrentHeaderBackground, contentTransparency) }, nls.localize('mergeCurrentContentBackground', 'Current content background in inline merge-conflicts.'));
+export const mergeIncomingHeaderBackground = registerColor('merge.incomingHeaderBackground', { dark: incomingBaseColor, light: incomingBaseColor, hc: null }, nls.localize('mergeIncomingHeaderBackground', 'Incoming header background in inline merge-conflicts.'));
+export const mergeIncomingContentBackground = registerColor('merge.incomingContentBackground', { dark: transparent(mergeIncomingHeaderBackground, contentTransparency), light: transparent(mergeIncomingHeaderBackground, contentTransparency), hc: transparent(mergeIncomingHeaderBackground, contentTransparency) }, nls.localize('mergeIncomingContentBackground', 'Incoming content background in inline merge-conflicts.'));
 
-export const overviewRulerCurrentContentForeground = registerColor('editorOverviewRuler.currentContentForeground', { dark: transparent(mergeCurrentHeaderBackground, rulerTransparency), light: transparent(mergeCurrentHeaderBackground, rulerTransparency), hc: transparent(mergeCurrentHeaderBackground, rulerTransparency) }, nls.localize('overviewRulerCurrentContentForeground', 'Current overview ruler foreground for inline merge-conflict.'));
-export const overviewRulerIncomingContentForeground = registerColor('editorOverviewRuler.incomingContentForeground', { dark: transparent(mergeIncomingHeaderBackground, rulerTransparency), light: transparent(mergeIncomingHeaderBackground, rulerTransparency), hc: transparent(mergeIncomingHeaderBackground, rulerTransparency) }, nls.localize('overviewRulerIncomingContentForeground', 'Incoming overview ruler foreground for inline merge-conflict.'));
+export const mergeBorder = registerColor('merge.border', { dark: null, light: null, hc: '#C3DF6F' }, nls.localize('mergeBorder', 'Border color on headers and the splitter in inline merge-conflicts.'));
+
+export const overviewRulerCurrentContentForeground = registerColor('editorOverviewRuler.currentContentForeground', { dark: transparent(mergeCurrentHeaderBackground, rulerTransparency), light: transparent(mergeCurrentHeaderBackground, rulerTransparency), hc: mergeBorder }, nls.localize('overviewRulerCurrentContentForeground', 'Current overview ruler foreground for inline merge-conflicts.'));
+export const overviewRulerIncomingContentForeground = registerColor('editorOverviewRuler.incomingContentForeground', { dark: transparent(mergeIncomingHeaderBackground, rulerTransparency), light: transparent(mergeIncomingHeaderBackground, rulerTransparency), hc: mergeBorder }, nls.localize('overviewRulerIncomingContentForeground', 'Incoming overview ruler foreground for inline merge-conflicts.'));
 
 // ----- color functions