@css
Hm, it's different in Safari vs. Chrome & Firefox. It seems like a bug but I don't know whether it's technically against spec or not.
In Safari, even though the DevTools shows the <a> element filling the grid area, only the link text is a click target. It might be a layer issue, the whole area is clickable if the image doesn't load or if z-index: 1 is added to the link.