diff --git a/src/vs/editor/browser/viewParts/indentGuides/indentGuides.css b/src/vs/editor/browser/viewParts/indentGuides/indentGuides.css
index d2785cebd6bae5d03eb2f12f0414af83ed21ffd3..45992137d182058608c31b496abf97c59d5e76c2 100644
--- a/src/vs/editor/browser/viewParts/indentGuides/indentGuides.css
+++ b/src/vs/editor/browser/viewParts/indentGuides/indentGuides.css
@@ -9,6 +9,4 @@
 */
 .monaco-editor .lines-content .cigr {
 	position: absolute;
-	--box-shadow-color: rgba(0, 0, 0, 0);
-	box-shadow: 1px 0 0 0 var(--box-shadow-color) inset;
 }
diff --git a/src/vs/editor/browser/viewParts/indentGuides/indentGuides.ts b/src/vs/editor/browser/viewParts/indentGuides/indentGuides.ts
index 608456fc4ab0114df0903ad9a41674e4fcbc1f70..b8ad9dadd68815d526f3406a52ba82ed3e337bab 100644
--- a/src/vs/editor/browser/viewParts/indentGuides/indentGuides.ts
+++ b/src/vs/editor/browser/viewParts/indentGuides/indentGuides.ts
@@ -130,6 +130,6 @@ export class IndentGuidesOverlay extends DynamicViewOverlay {
 registerThemingParticipant((theme, collector) => {
 	let editorGuideColor = theme.getColor(editorIndentGuides);
 	if (editorGuideColor) {
-		collector.addRule(`.monaco-editor .lines-content .cigr { --box-shadow-color: ${editorGuideColor}; }`);
+		collector.addRule(`.monaco-editor .lines-content .cigr { box-shadow: 1px 0 0 0 ${editorGuideColor} inset; }`);
 	}
 });
diff --git a/src/vs/editor/browser/viewParts/rulers/rulers.css b/src/vs/editor/browser/viewParts/rulers/rulers.css
index 30bb66bddd35031c705d3ab216c977c693aed8ba..d3d2d26ec95a3f8c6abb5f3ae0753781b38d7eaa 100644
--- a/src/vs/editor/browser/viewParts/rulers/rulers.css
+++ b/src/vs/editor/browser/viewParts/rulers/rulers.css
@@ -6,6 +6,4 @@
 .monaco-editor .view-ruler {
 	position: absolute;
 	top: 0;
-	--box-shadow-color: rgba(0, 0, 0, 0);
-	box-shadow: 1px 0 0 0 var(--box-shadow-color) inset;
 }
\ No newline at end of file
diff --git a/src/vs/editor/browser/viewParts/rulers/rulers.ts b/src/vs/editor/browser/viewParts/rulers/rulers.ts
index 49779199cff35f47493125d03140f27d67fefa86..bac590e81741a35b92a62022a5a9d94a11031cb9 100644
--- a/src/vs/editor/browser/viewParts/rulers/rulers.ts
+++ b/src/vs/editor/browser/viewParts/rulers/rulers.ts
@@ -103,6 +103,6 @@ export class Rulers extends ViewPart {
 registerThemingParticipant((theme, collector) => {
 	let rulerColor = theme.getColor(editorRuler);
 	if (rulerColor) {
-		collector.addRule(`.monaco-editor .view-ruler { --box-shadow-color: ${rulerColor}; }`);
+		collector.addRule(`.monaco-editor .view-ruler { box-shadow: 1px 0 0 0 ${rulerColor} inset; }`);
 	}
 });