CSS for hyperlinks & hyperlinked images

Hi,
In my sidebars, the hyperlinked images are not placed correctly. I am using the identical theme and style.css for 3 blogs, but the 3rd blog has the images misplaced. So, whatever the cause for this anomaly, I would like to correct it in the CSS file, unless there is an easier solution.

Right now, the hyperlinked images in the left sidebar are fixed on the left edge and in the right sidebar, on the right edge. I’d like each to be 7 pixels or so in from the left, for both sidebars, to be essentially centered (based on their size) in each sidebar.

What do I look for in the style.css file that is controlling this and what do I need to edit to attain the desired result? Is there a preferable solution to editing the css file?
many thanks in advance,
Sue