Animation not working when accordion is in iframe #92

I have a situation where we used your rc-collapse in our web app and in development it worked great. For some reasons we need to put it in iframe, and after we did it animation stopped working.

Accordion is still opening and closing tho, but without animation. It seems to me that it doesn't set the initial height (by inspecting it in Chrome), only final height. For example: when I want to open it first time, it only sets height: 200px. But without iframe, it correctly sets first 0px and 200px after that, so animation works.

Do you know why this might be happening?