It is most likely down for maintenance. No big deal. It happens from time to time on the exchanges. You can click on the box next to it and a lot of times it will have a drop down mesage that tells you what the issue is and why it is offline.
Yes it goes offline. I dont know why, but i need to re-verify my identity again :\
I don't know too when it will be online again. Maybe they will make KYC procedure more stringent.