How to make a C# menu bar act like Chrome's bar?

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C#

menu

bar

I am doing a UI design for my project
it's the C# web application and I use VS2010 for developing
I choose to use the "web form using Master Page" and thus there is a master menu bar.
I wish to make it look like the chrome's menu bar, which mean one of the menu items will keep look different with others since I'm accessing that page.

I would like to use the css page for it,
thus the question should be:
How to keep a menu item in a hover stage when I accessing that page?

hope you guys understand my words,
thank you!