Layers Breadcrumb: fix extra space in small screens

Before:
![screen shot 2014-10-17 at 10 47 06](https://cloud.githubusercontent.com/assets/1152640/4676383/43b07ce2-55da-11e4-8cf3-ad6c4cf1123d.png)

After
![screen shot 2014-10-17 at 10 47 22](https://cloud.githubusercontent.com/assets/1152640/4676382/43aa71e4-55da-11e4-9ab3-bac389ebe17d.png)

The extra space above the nav is not due to the ad... 

This is coming from here https://github.com/lonelyplanet/rizzo/blob/master/app/assets/stylesheets/core/layouts/modern/_secondary_nav.sass#L45

I was going to remove that `position:static` but may affect a lot of pages... so, I did a override in layer styles...