Collapsible elements behave differently on different browsers

[Princu7]

I came across this bug while I was solving a previous issue. The bug can be best demonstrated with the help of some screenshots.

On Chrome (or any Chromium based browsers)

In the rooms page, if I click on any session, it expands correctly and then collapses correctly on clicking again. Here are the screenshots:

On Clicking the session element (In this case 'Opening Speech')

On Clicking Again to collapse

On Firefox

On Clicking any session element(it expands normally)

But it doesn't collapse correctly. It creates an empty space. (only first session of the page collapse correctly)

I am working on this issue.