
1. .tab-text { font-family:'Lucida Grande', 'ヒラギノ丸ゴ Pro W4' !important;}
2. .tab-text { font: small-caption !important; font-weight: normal !important; }
3. .tab-text { font:icon !important}
Notice how the Japanese text is smashed and pixelated in [2] and [3].
In [1], my prefered font-choice, I force the default cascade built in by the OS.
Due to font-smoothing, the contrast is less high, especially in the first tab, and more so on a Powerbook. Note: I've installed this theme on my desktop Mac as well, where the contrast problem is much less (23inch Apple monitor).
The expander arrow, looks more like the OS made one.

[edit] Almost forgot. The above screenshots are made with your background image.
A better result on my side (Powerbook 15inch) is this. I made the darkgrey 10% lighter (use #999999 instead of #808080, if that is too light #8C8C8C gives good results as well).