Strangely I am having a problem to log in. Does anyone here has the similar problem?

---the details of the problem------
1. I can access  bitfinex and surf the website.
2. when I click the buttons of log-in or sign-up, there are no pop-up showing up.
3. Then I try to click the button of open account, a pop-up window showed up.

Could anyone help and explain what is happening? Thanks