Alignment issue in Right sidebar

Hello

I use the Right Sidebar for advert graphics.
The problem is that the graphics align to the left and not centre as I want.

The CSS for this area is
border-left: dashed 1px #CCCCCC;
padding: 10px 10px 10px 20px;
background: #f7ece3

The graphics are set for 100% width and the sidebar width is set at 340 px.

I have tried changing the width and alignment setting on the graphics but it makes no difference.

There seems to be some other setting which controls the behaviour but I don't know what it is.
You can see the problem here ...


Help appreciated as usual.
TF