Twitter/Facebook/Tumblr count down characters is hidden by the picture of the post. Close #3956

#3956

Another Pull Request https://github.com/diaspora/diaspora/pull/3958

![Captura de pantalla de 2013-02-04 21:25:16](https://f.cloud.github.com/assets/1108789/125124/2ffbc16a-6f0a-11e2-99f2-dd71bcb95fb2.png)