I'm not sure if this a bug or a concious design decision.
In the initial design proposal, the color of the "bounty tag" was adapted to the general color scheme of the site, thus it used some kind of cyan/green-blue instead of the classic blue, which seemed to fit very well:
But in the final version, we're back at classic bounty blue:
Was this forgotten to adapt or was there a particular reason this idea was dropped? Did it maybe violate existing SE practice too much (yet, there are other more extreme sites where the bounty color is red)?