I don't understand what the problem was (#0000 being the colour black, isn't it?), but the solution apparently works.
#0000 is a colour attribute of the form #ARGB, where A is the alpha channel, i.e. the opacity.
So #0000 represents a colour that is technically black, but fully transparent (0% opaque).
Whereas fully opaque black would be written as #F000 in this format (the ‘F’ being shorthand for #FF or 255, the maximum value for an unsigned byte).
Edited by andrewbroad, 27 November 2017 - 01:47 AM.