Does anyone know of any testing / studies with evidence that Google prefers dark text on a light background vs. light text on a dark background?

I have a website that currently has light text on a black background, and really like the way it looks, but am concerned that the style may be hurting SEO.

Moreover, redesigning something inverse with the same quality would be a large project and fairly costly, so I'd like to make sure the benefit will really be worth the cost before moving forward.

If you look at most of the Facebook comment implementations, they're usually embedded with an iframe.

Technically speaking, that is making the content load from another source (not on your site).

As we're constantly seeing Google evolve with regard to "social signals", however, I suspect embedded Facebook comments may begin to have an impact if they pertain to content that is actually located on your website.

I didn't see any recent test for 2013, but it's been analyzed quite a bit, and the 2 links below expand a bit on what I mentioned.

The conclusion on the first one below is that it won't index content loaded dynamically from a javascript file on another server/domain.

http://www.seomoz.org/ugc/can-google-really-access-content-in-javascript-really

Here's the link that talks about extra programming necessary to make AJAX content crawlable and indexable.

http://support.google.com/webmasters/bin/answer.py?hl=en&answer=174992

Googlebot has become extremely intelligent since its inception, and I'd guess that most members here would probably agree that it's gotten to the point where it can detect virtually any type of content on a page.

For the purposes of analyzing the actual content that it indexes and uses for ranking / SEO, however, I'd venture to guess that the best test would be viewing the page source after the page has loaded.

If you can see the content you're questioning in the actual HTML, then Google will probably index it, and use it considerably for ranking purposes.

On the other hand, if you just see some type of javascript snippet / function where the content would otherwise be located in the page source, Google can probably read it, but won't likely use it heavily when indexing and ranking.

There are special ways to get Google to crawl such content that is loaded through javascript or other types of embeds, but it's been my experience that most embeds are not programmed this way by default.