Here is the block of CSS that seems to be creating problems:
margin: 0 auto;
border-left: #000 3px solid;
border-right: #000 3px solid;
On my homepage, it creates a nice 3-px border and looks fine: http://www.steenface.com/
But on my other two pages (About & The Others) the left border is doubled like so: http://www.steenface.com/?page_id=548
I had to insert the border-top: none; line to get rid of the black line at the top but if I do the same to get rid of the border-left, it erases the left border completely from my home page.