The Aqua interface has been a staple of Mac OS X since version 10.0, but now it appears that Apple is toning down the Aqua appearance of its operating system in Mac OS X 10.7 Lion. As you can see from the screen shot above, Apple has removed a lot of the Aqua trimmings from drop-down menus; it has also taken the pill-shaped Aqua buttons and given them a more flat, rectangular appearance.
In addition to the changes above, Lion has also stripped out OS X's Aqua scroll bars and replaced them with iOS-like scroll bars that fade away when not in use. The white pill button found in the upper-right corner of a Finder or app's window, which shows or hides a window's toolbar, has also now been replaced with a full-screen button.
I'm a fan of the new look myself. I'm glad Apple hasn't totally abandoned the Aqua interface, but it's nice that it's been toned down. If you want to see more of the subtle changes listed above, click on over to AppleInsider, which posted the above images.
Apple OS X Yosemite