Having issues with images uploading

To Whom it May Concern,

I am having some trouble with getting some banner images to load at the top of my site. Specifically the pages are:

http://art2lifeacademy.com/faq/
http://art2lifeacademy.com/18-community-guidelines/
http://art2lifeacademy.com/art2life-academy-team/
http://art2lifeacademy.com/resources/

I can see where I have uploaded the images from the back end of my site, but when I look at the front end, the images are not uploading. Any idea why this might be happening? There were some changes that were made in the simple CSS plugin. Could any of that be causing this?

I look forward to your response.

Best, Nicholas