Nope, it traverses up the DOM until it finds an element which has any non-transparent background. If the first thing it finds has a background-image, it aborts. If it’s a solid color, it returns that container. [1]
This absolutely still is prone to bugs when `position` or other properties are used to move elements visually outside of their parents, but it’s about as good as you can do without a true HTML-to-canvas implementation.