In the past few days I had problem with facebook display in my Firefox. The top and the bottom bars were become transparent. The content of the facebook could be seen through those bars. Looks like it has problem with it’s Javascript. Both of my Linux and Windows system had this problem.
In the first day I thought the problem was because a problem in Facebook. After a few days I noticed that some of my friends didn’t have problem with Facebook, even though I didn’t know what browser that they used.
Yesterday I fixed the problem. Looks like it because the offline website data in my notebook cause the problem. Yesterday I cleared all the caches, cookies, and offline website data, and then my facebook’s look backs to normal.