Bug 929031 fixes for lightbeam page after push

Some further fixes/cleanup for the Lightbeam pages:

* Standardized and optimized image sizes & positioning
* Cleaned up some layout and spacing issues

Note: I didn't go as far with removing some of the less semantic CSS class names as I would have liked, as many of these also have dependencies in the database/profile pages. Because these pages are not yet working, it means we can't really test the changes very easily. For this reason I decided it's probably not worth refactoring the class names with this PR. Perhaps if/when the other pages are enabled again we can revisit this.