src/vs/platform/theme/electron-main/themeMainService.ts/ThemeMainService/getBackgroundColor
class ThemeMainService:	getBackgroundColor(): string {
		if ((isWindows || isMacintosh) && nativeTheme.shouldUseInvertedColorScheme) {
			return DEFAULT_BG_HC_BLACK;
		}

		let background = this.stateMainService.getItem<string | null>(THEME_BG_STORAGE_KEY, null);
		if (!background) {
			let baseTheme: string;
			if ((isWindows || isMacintosh) && nativeTheme.shouldUseInvertedColorScheme) {
				baseTheme = 'hc-black';
			} else {
				baseTheme = this.stateMainService.getItem<string>(THEME_STORAGE_KEY, 'vs-dark').split(' ')[0];
			}

			background = (baseTheme === 'hc-black') ? DEFAULT_BG_HC_BLACK : (baseTheme === 'vs' ? DEFAULT_BG_LIGHT : DEFAULT_BG_DARK);
		}

		if (isMacintosh && background.toUpperCase() === DEFAULT_BG_DARK) {
			background = '#171717'; // https://github.com/electron/electron/issues/5150
		}

		return background;
	}