jQuery Button Slide Down Animation is pushing the other set of buttons??

jQuery Button Slide Down Animation is pushing the other set of buttons??

the buttons in the homepage are pushing the other buttons, any one has an idea on how to make the buttons slide over the other ones and not push them
see my website file at my google drive
https://docs.google.com/folder/d/0B-C0T_-acxRqeDBEOWpSdWZYYUU/edit