Fixed Carousel Images in index.html

For both images, I set: 

margin: 0 auto;

For most images, I think we should set min-width to be 100%; however, because the Optimir logo was significantly smaller than the Cal @ Night photo, with a min-width of 100%, the picture resolution diminished greatly. So I set the max-width: 100%. Now both pictures are centered and conform well to the size of the page.