src/vs/base/browser/dom.ts/getDomNodeZoomLevel
export function getDomNodeZoomLevel(domNode: HTMLElement): number {
	let testElement: HTMLElement | null = domNode;
	let zoom = 1.0;
	do {
		const elementZoomLevel = (getComputedStyle(testElement) as any).zoom;
		if (elementZoomLevel !== null && elementZoomLevel !== undefined && elementZoomLevel !== '1') {
			zoom *= elementZoomLevel;
		}

		testElement = testElement.parentElement;
	} while (testElement !== null && testElement !== document.documentElement);

	return zoom;
}