Navigation overlaps product image

By default the left and right navigation arrows overlap the product images in the slider, but I’d like for the left arrow to be to the left of the slider and the right arrow to be to the right of the slider. If I try to reposition them with css, they disappear, since the container has overflow: hidden. I’ve tried editing the markup in related.php and adding an additional container so the navigation buttons can be outside the main container, but then the navigation doesn’t work. Can you recommend a solution?