Anyhow, as mentioned above the Oxygen theme is the default theme that the KDE4 uses which does resemble a lot of similar look-n-feel concerning the Mac OSX (it kinda slipped out :P) and the colors certainly are easy on the eyes too. It's a complete theme suite which comes with an icons, wallpapers and the GUI buttons and the "tinting".
But as any obsessive theme geek knows ;-) even after having a complete theme installed still if you have a major application that you frequently use which does not inherit the look-n-feel of the main desktop theme... well it can easily jeopardize everything.
Now the web browser is such an application nowadays thus if you use KDE 4+ as your main desktop and use the Firefox 3-5 as the web browser, then you might be wondering if you could find a way to "Oxygen-lize" its skin :D.
Well no worries dudes... there is in fact an Oxygen KDE theme for Firefox web browser that does exactly that!. Few hours ago they've released the latest version 3.2 which now supports the Firefox 5, finally. Anyhow the 3.x version comes with few improvements in general such as ...
|Don't you just love it ;-)...|
*. Automatic color scheme detection under KDE (say that you've changed the default colors of the Oxygen theme, then the browser add-on/theme will change automatically).
*. 4 Additional styles for buttons.
*. Classic Oxygen + the shadowed version.
*. 3 Styles for the background.
*. Hide/unhide arrows.
*. Also supports the now old Firefox 4.
*. Comes with a Linux/KDE configuration window of its own which lets you change a lot more other options.
*. 2 Different icon themes... are just a few to mention.
As you can see from the above screenshot, once installed this theme, it'll make the Firefox web browser "theme integration" with the Qt-KDE Oxygen desktop almost perfect. If interested (heck yea you are :D) you can get the stable version from this KDE-app page. Enjoy.