Thanks.
The screen shot was indeed from that URL.
Unfortunately, though the change you suggest helps, there are still some problems. Below are two screen shots, first with your modification, the second without:
Comparing the two, you can see two problems:
1. The greenish/brownish border outside and directly to the left and right of the signature block/box is thicker than the border around the rest of the post area.
2. Below the signature, the area is still darker than the rest of the post area.
Sorry my template is so troublesome.

I assume you may need me to post some code from my template. Please let me know if that is so, and from what file.