(Newby)
On my site I have an event registration component I purchased that has a "Add To Calendar" button. It has a couple of issues:
1) The button does not work when forcing SSL. It just disappears on all browsers except for Safari.
2) Under the conditions that it is visible it has no formatting and appears as a plain vanilla button.
You can see a live example at:
http://mieventoonline.com/index.php/events/submenues-configuration/event-list/event/5/Ponce-MTB-Challenge