folded background uses transparent selection color. Fixes #88070, fixes #87891

src/vs/editor/contrib/folding/folding.ts

@@ -32,6 +32,8 @@ import { InitializingRangeProvider, ID_INIT_PROVIDER } from 'vs/editor/contrib/f
 import { KeybindingWeight } from 'vs/platform/keybinding/common/keybindingsRegistry';
 import { onUnexpectedError } from 'vs/base/common/errors';
 import { RawContextKey, IContextKey, IContextKeyService } from 'vs/platform/contextkey/common/contextkey';
+import { registerThemingParticipant } from 'vs/platform/theme/common/themeService';
+import { registerColor, editorSelectionBackground, transparent } from 'vs/platform/theme/common/colorRegistry';
 
 const CONTEXT_FOLDING_ENABLED = new RawContextKey<boolean>('foldingEnabled', false);
 
@@ -884,3 +886,12 @@ for (let i = 1; i <= 7; i++) {
 		})
 	);
 }
+
+export const foldBackgroundBackground = registerColor('editor.foldBackground', { light: transparent(editorSelectionBackground, 0.3), dark: transparent(editorSelectionBackground, 0.3), hc: null }, nls.localize('editorSelectionBackground', "Color of the editor selection."));
+
+registerThemingParticipant((theme, collector) => {
+	const foldBackground = theme.getColor(foldBackgroundBackground);
+	if (foldBackground) {
+		collector.addRule(`.monaco-editor .folded-background { background-color: ${foldBackground}; }`);
+	}
+});

src/vs/editor/contrib/folding/foldingModel.ts

@@ -6,9 +6,6 @@
 import { ITextModel, IModelDecorationOptions, IModelDeltaDecoration, IModelDecorationsChangeAccessor } from 'vs/editor/common/model';
 import { Event, Emitter } from 'vs/base/common/event';
 import { FoldingRegions, ILineRange, FoldingRegion } from './foldingRanges';
-import { registerThemingParticipant } from 'vs/platform/theme/common/themeService';
-import { registerColor, editorSelectionBackground, darken, lighten } from 'vs/platform/theme/common/colorRegistry';
-import * as nls from 'vs/nls';
 
 export interface IDecorationProvider {
 	getDecorationOption(isCollapsed: boolean): IModelDecorationOptions;
@@ -357,12 +354,3 @@ export function setCollapseStateForType(foldingModel: FoldingModel, type: string
 	}
 	foldingModel.toggleCollapseState(toToggle);
 }
-
-export const foldBackgroundBackground = registerColor('editor.foldBackground', { light: lighten(editorSelectionBackground, 0.5), dark: darken(editorSelectionBackground, 0.5), hc: null }, nls.localize('editorSelectionBackground', "Color of the editor selection."));
-
-registerThemingParticipant((theme, collector) => {
-	const foldBackground = theme.getColor(foldBackgroundBackground);
-	if (foldBackground) {
-		collector.addRule(`.monaco-editor .folded-background { background-color: ${foldBackground}; }`);
-	}
-});