Currently you have no content in that section, just empty divs and links with background images. All elements with nothing in them have a height of 0. You can see them in the design because if you couldn’t people would be loosing elements all the time.
You will need to add content to those links or assign a height to them. I would suggest braking up your background image and creating the button using CSS. The only thing that needs to be an image in the computer icon.