Not able to apply for a job

I'm not able to apply for this job https://stackoverflow.com/jobs/121524/senior-software-engineer-backend-shopback. When I click on the apply now button, it doesn't show anything. I have tried this in Firefox 49.0 and Google Chrome 53.0.2785.143 on Ubuntu 14.04.

Any help is greatly appreciated.

UPDATE:

Following errors are shown in the console:-

However, it works fine when accessed via HTTPS protocol, https://stackoverflow.com/jobs