twenty twelve header transparent

Hello,

Here is my website: https://www.genestival.fr/.work

I wish to make the header transparent so that we can see the background behind.

I put up the picture of the current website
https://drive.google.com/file/d/0B0mPv3TQMVwGZWxZWEZOV2MzdmM/edit?usp=sharing

And here is the image of the site as I would like it
https://drive.google.com/file/d/0B0mPv3TQMVwGTm9IVHZhM3FGUnM/edit?usp=sharing

Excuse me for my English, I use a translator.

Hankey

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