You can download the Yosemite Transformation Pack for free and its didn't have much size also, its only of 110 mb. Its very simple to install the Transformation Pack, as you have to just run the .exe file and proceed the installation process. After the installation complete, restart your system, so that Pack fully customize your system.
Make Windows Look like Mac OS X Yosemite - Transformation
Transform Windows to Look like Mac, OS X Yosemite Preview: Apple's Windows 8 Antidote, OS X Yosemite Transformation Pack For Windows 7/8.1, Make Windows Look like Mac OS X Yosemite, OS X 10.10 Yosemite features translucent windows