That is perfect. At last I could make my Firefox looks like Windows edition.
However, installing Stylish and its styles just affects on the minimize, maximize, close buttons shape. Since it does not necessary for me, I prefer to not to install Stylish and I skiped the fourth step.
Moreover, we need to edit the code in the fifth step. The final version of Firefox 4 has released and you can install the stable PPA here:
Since it is the final version, Ubuntu does not call it as Minefield anymore. Thus, we need to replace the Minefield part as Firefox in the fifth step:
That's all... The screenshot is in the attachment...
any & !(class=Firefox & state=maxvert)