I noticed that the problem with the long posts stretching out the page has been fixed. ^^
However, and I don't mean to moan, but the fixed width still bothers me. :/
Most people these days do not use such a small resolution. Could I perhaps suggest that it is done in the same way as "Bellossom Shower"?
What I mean is, where "Bellossom Shower" has this for a background for the banner:
This Delibird theme could have this:
(Black CSS background to show transparency)
Then, "Bellossom Shower" has two images over the top of that, one aligned to the left, and the other to the right.
For this new theme they could be...
(Black CSS background to show transparency) Left:
(Black CSS background to show transparency) Right:
And finally, instead of the current background image:
You could have a solid colour of....#9a262a? Which is an appropriate colour for the banner background to fade to.
All of this means it can retain its primary looks, but at the same time be a dynamic width style.
These images obviously aren't as good as they could be, but they are the best I could do without the PSD source.
This is just my idea, and I guess ultimately it comes down to you, but I hope that you'll take this into consideration. :)