Scrolling doesn't work on the main page

Steps to reproduce:
1. Open Antarcticle main page (http://qa.jtalks.org/antarcticle).
2. Scroll down.

Actual result:
The scrolling function doesn't work.

Expected result:
There is an option to scroll down.

3. Open the next page
4. Scroll down

Actual result:
The scrolling function doesn’t work.

Expected result:
There is an option to scroll down.