Slider controls float over slider image at some viewport widths

Hi! Just bought the theme last month and working on customizing. On my site, the slider controls (<- PREVIOUS 1/4 NEXT ->) float over the image unless the browser view is zoomed to 125% or greater. I tried adjusting the CSS on the slider-controls class, but nothing helps. Can you fix this? URL is http://ps281.wpstagecoach.com/ Thanks! -David