Fixed callout image surfacing on search

The callout image for the new jobs board was z-indexed above the
search modal background. I sent it down a notch.

![:'(](https://photos-3.dropbox.com/t/0/AABTHSM8TQqEdArEvvJ6T3VLBNwDtHr30ipFNU0GxvVCfw/12/20720/png/1024x768/3/1400295600/0/2/Screenshot%202014-05-16%2021.40.43.png/e7Ysdc51eohUj6Pc-f9y_8hNeURpsxsZhoKIptaDkuw)