src/vs/workbench/browser/parts/editor/editorPart.ts/EditorPart/updateStyles
class EditorPart:	override updateStyles(): void {
		const container = assertIsDefined(this.container);
		container.style.backgroundColor = this.getColor(editorBackground) || '';

		const separatorBorderStyle = { separatorBorder: this.gridSeparatorBorder, background: this.theme.getColor(EDITOR_PANE_BACKGROUND) || Color.transparent };
		this.gridWidget.style(separatorBorderStyle);
		this.centeredLayoutWidget.styles(separatorBorderStyle);
	}