Hi Nikeo - first and foremost well done sir on your theme!
In a shop where I would like to use this as it's blog format, testing with many browsers now encountering the same error an IE8, it causes all the posts on the main page, specifically the title to extend beyond their fields (attaching error to help in any capacity):
On a side note to get IE 9 to play ball with the slider alignment I seemingly have had to remove your "if IE7/IE8" lines within header.php (please correct me if I am on the wrong path on that one!):
IE 8 error:
Webpage error details
User Agent: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; WOW64; Trident/4.0; SLCC2; .NET CLR 2.0.50727)
Timestamp: Mon, 29 Jul 2013 19:04:19 UTC
Message: Function expected