As Designed/Not a Bug Tables Have No Heading Background

Previously, [TH][/TH] would center the text ("Date" and "Last Activity" in the example below) and have a different background than the rest of rows to distinguish them from the [TD][/TD]. However, while the centering is still there, the different background appears to be gone in this style.

Code:

[TABLE]
[TR]
[TH]Date[/TH]
[TH]Last Activity[/TH]
[/TR]
[TR]
[TD]2/23/2014[/TD]
[TD]2/24/2014 at 12:02 AM[/TD]
[/TR]
[TR]
[TD]2/24/2014[/TD]
[TD]2/25/2014 at 12:00 AM[/TD]
[/TR]
[TR]
[TD]2/25/2014[/TD]
[TD]2/26/2014 at 1:01 AM[/TD]
[/TR]
[TR]
[TD]2/26/2014[/TD]
[TD]2/27/2014 at 2:06 AM[/TD]
[/TR]
[TR]
[TD]2/27/2014[/TD]
[TD]2/28/2014 at 12:30 AM[/TD]
[/TR]
[TR]
[TD]2/28/2014[/TD]
[TD]3/1/2014 at 3:10 AM[/TD]
[/TR]
[TR]
[TD]3/1/2014[/TD]
[TD]3/2/2014 at 12:01 AM[/TD]
[/TR]
[/TABLE]