On the item show page the Back to Search does not look like a button

[christinach]

Descriptive summary

In the current GeoBlacklight 2.0 master branch, it seems that the Email icon is not showing on the toolbar.

Expected behavior

On the show page of an item, the 'Back to Search' link should be displayed like a button.

Actual behavior

On the show page the 'Back to Search' displays like a link when you hover over the text.