As you have probably noticed, transparency is a pretty common trend in web design and I myself think it looks pretty stylish. It adds up character and individuality to a design, even if it adds up in popularity between web designers.
You can play with the opacity on the menu or different other elements from you design and make it as transparent as you think it look best of all. You can play with tones and lighting of the transparent elements in your design and get the wanted effect. It really reminds me of the interface of Windows 7, and I can say that its design is my favorite so far.
There are several methods that you can achieve this effect and it is not complicated at all, you just have to find the perfect combination and a way to integrate it with your design. This post will showcase some pretty cool examples of transparency in web design.
Transparency in Web Design