Is it posssible to change the position of the caption relative to the image? My captions appear too far beneath the image for my liking and I would like to close the gap between them. Can this be done?
In a word, no. The caption is positioned relative to the viewport, i.e., the browser window. It's simply anchored to the bottom of the screen. It doesn't know or care how large the image is.
It sounds like the real problem is that you're using original images that are too small and/or using image bounds that are too small. With sufficiently large images, the image will be shown as large as it can be, given the size of the viewport, and the caption will be directly beneath it.