Comment 32 for bug 1986450

> .background.decorated:backdrop {

This still doesn't feel entirely good. The background can be applied to a window, in which case it needs to be restricted to the .decorated property; but I presume it can also be applied to many other GTK widgets in which case it shouldn't be restricted, at least in order not to change the current behavior because I don't know how to test any change.

So if I'd like to perform the smallest possible change, the smallest possible impact of the change (preferably: no other change than fixing this bug) then I'd need to select for "either window.decorated or something non-window", which I'm not sure how to express in CSS (at least not in a single step).

Maybe leave the first block untouched, and then revert its effect in the next rule for undecorated windows (effectively moving the above-proposed user workaround into the main theme, restricted to the element being a window).

So the theme itself would go like (the first block is unchanged, the second one is newly added):

  .background:backdrop {
      color: @backdrop_fg_color;
      box-shadow: inset -1px 0 shade (@bg_color, 0.94);
  }

  window.background:not(.decorated):backdrop {
      box-shadow: none;
  }

Dunno how much it makes sense. Would really love to get it reviewed by a CSS expert :)