Why are Back/Fwd buttons so lo-contrast?

This is going to sound like the ultimate nit-pick, but is there a way to edit the appearance of the Back and Forward buttons in Safari? I find that in the new version of Safari, the contrast between the arrow and the button is not dramatic enough. I have trouble telling whether or not I can go back, or if I'm at the end of the line, so to speak. I never thought anything of this particular UI nugget, but in the recent changes of v5.1 (Lion), I'm confronted with it. This is a classic example of never noticing something until it breaks.

Ok, here's some visual examples:

Existing Back/Fwd buttons. Very hard to tell that Back is enabled, but Fwd is not.

My proposed changes. Here, the Back button is clearly visible in comparison to the Fwd, which is not available in this case.

I've tried to poke around in the Package Contents, and it seems as if every other UI element is there, somewhere, except the Back and Forward buttons. A number of buttons do exist in the various folders, but they all seem to be shades of blue, and reversed, set with white arrows on blue buttons. I'm confused.

Any insight you have as to how to get to the real images underneath those buttons is helpful. This is killing me.