Sliding Tabs Nav

Hi everyone,

There’s similar posts out there but none have been able to solve my problem.

I’m trying to create a sliding tabs nav. For an example go to

www.howster.com/work/cytest

Click on the orange section and then try rolling over the nav on left hand side. It’s supposed to grow and push the other buttons aside. Once you click on that section, the transition to that section will occur and that particular button will STAY expanded until you click on another section. Does anyone know of any tutorials for this? Or can anyone lead me in the right direction for the concept? Thanks guys!