Menu bar on web pages not visible in Safari

I am facing this problem when ever I am visiting any website that has go a Menubar on the top, then the part remains half invisible in Safari.

See below:

Here is screenshot of SoF site on Safari:

Facebook pages:

and Quora:

Anyone else faced similar problems? Any resolution to this?

OS: Yosemite Version 10.10.2

Browser: Safari Version 8.0.3