Page content alignment detection

I am working on a web tracking solution and I need to know the content alignment inside a web page.

e.g:

• https://www.google.com - google search in centered
• http://ift.tt/gbk8l4 - centered
• http://ift.tt/1nzwNIW - positioned left

Does anyody have an idea how to do this automatically?

I have thought about detecting the html elements by javascript, or computer vision (preferably client side).

Cheers, Tibor