Hi deotpit, you are right, it is the text-align vertical-align that does the image positioning.
My margin-comment was unclear in what was arbitrary, I think:
margin:0 -552px 0 -526px; /* To keep the middle image centred: give the side margins the same length-difference as of the outer images, the additional length is arbitrary */
What I tried to say was; In order to make the image-container wide enough to not wrap the images when the #title_wrapper gets narrow, the negative side margins extends its width by an arbitrary length enough to keep the images on the same line.
I also thought the middle image should be in the exact centre of the window, but as the center-align applies to the group of images it would be off centre due to the different width of the two adjacent images.
So, to keep the middle image in the exact centre, the margin on the wider image's side needs to soak up the difference. (The "arbitrary" extended margin-values' was meant to reflect the different width of the two images. )
There are other ways to achieve the same result, but this was the easiest cross-browser I thought.