[Bad Bunny]

The reason you experience this "problem" is because the postbits are not really in the table that displays the background color. Ever notice how a really long post still has the borders around it? You have to do a bit of hacking in the postbit realm to get rid of the columns with spacers in them, and in the showthread realm, you have to place the postbits back inside the main content table.

Do it...go look at a really wide post, you will see that the page border shifts along with it. Otherwise, you are going to have an issue with the page border stretching to fit the wodest post.