box-shadow: insert bei Bildern
box-shadow: inset ist bei Bildern etwas tricky:
Browsers allow box-shadow on
elements, so why not just use an inset box-shadow on it.
Turns out, you can use inset box-shadows on images, it’s just the browser sets it behind the image, which mean if you use a fully opaque image (very likely if you are interested in vignetting it), you won’t see the shadow at all.