Get full width image in slider

Dear Sakin, I've searched this forum but i couldn't find an answer. First of all: Great theme! In the preview pictures, i see you have an image in your main slider which covers the full width. When i use a featured image, i still have a (blue) space on both sides of my image. I would like my image to be the full width. I'm using the right dimensions as suggested. Website: http://www.reisgidscambodja.org/