Say, for example, I have a <body> with a photo of my failed marriage, and on top of that I have a semitransparent <div> with background: rgba(0, 0, 0, .5):
I want to make a screenshot of that <div> as a 32 bit PNG, with no photo of my failed marriage showing through, only the half opaque black of the <div> itself:
I am not entirely sure but Firefox can do that, except it doesn't preserve the transparency:
Instead, Safari can do exactly what I want, if I recall correctly.
Is there some extension I could use?