This is the final design and concept, I just need to make some changes in the text.
This mail is available in:
In case you wanna check out the code, I didn´t add useful comments to learn to make this. Sorry,
In this case I used a lot of css3 code and looks like it works for Mail in OSX and iOS. So I think it also work for gmail.
Which are the most important in this case.
Anyway I was thinking to make the img radius with webkit, but to make it simple I just made it in photoshop with a mask.