Ok, here comes the trickiest part: to create the arrows. What we are going to do in order to accomplish this task is:
Use CSS to transform each bullet into an arrow sign by changing its shape and using a nice background image.
Move all the arrows to the left of the picture, one above the other. In this way, the only visible arrow will be the one corresponding to the picture with the highest index.
Hide the arrow corresponding to the selected image.
Move all the arrows that follow the one corresponding to the selected image to the right, one above the other. In this way, on the left side there will remain only those arrows that correspond to the pictures with index lower than the selected one (for example, if we select picture number three, only the arrows of pictures number one and two will stay on the left, with the arrow of picture number two on the top of the stack).
Pick the arrow that follows the one corresponding to the selected image and change its
z-index
value...