Top button links not displays. How can i display it?

Hi

my website is http://web.guru99.com/

now the top button link at footer is not displays at main page as well as various pages

here is the link where top button link not display

1) http://web.guru99.com/
2) http://web.guru99.com/php-tutorials/
3) http://web.guru99.com/demo-editor-php/

here you can see what i am talking about – http://i.imgur.com/PiGAwOx.png

now i am using chrome version 29.0.1547.76
So please help me to do so