Featherlight is a very lightweight jQuery lightbox.
This is a default featherlight lightbox. It's flexible in height and width. Everything that is used to display and style the box can be found in the featherlight.css file which is pretty simple.
It's easy to override the styling of Featherligh. All you need to do is specify an additional class in the data-featherlight-variant of the triggering element. This class will be added and you can then override everything. You can also reset all CSS: $('.special').featherlight({ resetCss: true });
With little code, you can build lightboxes that use custom content loaded with ajax...