The above screenshot is of the leather skin in the Calendar and Contacts apps that Apple introduced in Mac OS X 10.7, Lion. Since then, many people have disputed over the look and feel of those two apps. Some people like the idea that the Calendar and Contacts app (or previously known as the iCal and Address Book apps) have changed appearance to emulate the appearance of real-world planners or day trackers. On the other hand, there are others who believe that because it is a digital product, the nuances of having a leather bound book to keep track of events should not be emulated in the digital world. Regardless of where you stand, if you would like to get rid of the brown leather skin and change it back to the old aluminum skin for the Calendar or Contacts app, then follow the steps below.
2) Make a copy of the Calendar and Contacts app on your computer. Copy and paste these files to another directory to keep safe in case you want to revert back to the leather version.
3) Install the .dmgs and they will replace the images over the apps. Note: this does not remove/change the brown font. The brown font is now on top of the aluminum skin which some people may find weird.
4) If you would like to restore the original leather theme, simply delete the edited versions of the apps and copy the original versions that you had backed up earlier, back into the ~/Applications directory.
If you have any questions about the process or how it works, please leave a comment below!