Kuroi,
Thanks for comprehensive response.
The reason you cannot see this online is that I am working on a test site that will have a completely different look and feel from the one online.
I am showing credit cards images (merged into one) inside the editable sidebox.
I started out with an image 150px wide, which is the max width allowed for sidebox, and, yes, it did overflow, probably for the reasons you explained.
So I cropped image to 141px and now it is inside the sidebox.
Still don't understand why I cannot center it exactly, will continue testing settings.
The padding 0.4em is inserted in there by the standard Zen Cart stylesheet, and if I change that setting it will have site-wide effects.
I am enclosing a screenshot of the image.
Bookmarks