使用Mandrill api发送邮件更改格式

I am sending mails with Mandrill api in php. I create templates on MailChimp and then export them on Mandrill.

The visualisation is ok, and when I copy / paste the html-css code in a local file, everything works fine and it's beautiful.

When I send a test mail with MailChimp, it's ok too. But when I send a real mail / test mail with Mandrill, margins are gone :

the good one in local and the wrong margins one

Does anybody why is this difference ?
Thanks a lot

EDIT
I need to add that in Thunderbird i don't have margins problem anymore

It appear it was because gmail (and maybe others) doesn't interpret all css as an html page will do.

I found some cool tool that converts my mail code to inline css code : http://premailer.dialect.ca/

EDIT

https://stackoverflow.com/a/30545587/4617961