Why does Safari display the letter combination 'fi' as 'if'? I just came across a curious display error and was wondering what may cause it.
In Safari the following webpage Cross-Country Skating: shows a strange behaviour.
     
But the source code does not show this error:
... America’s Bill Koch first observed ...
... climaxing in a telegenic finish ...

Neither does Google Chrome:
    
Can anyone explain this behaviour?

System:
MacBook Air (MacBookAir3,1)
Intel Core 2 Duo; 1,6 GHz
OS X 10.11.2 (15C50)
Safari Version 9.0.2 (11601.3.9)
This is probably a problem with Safari font rendering engine with Merriweather Sans font. It has something to do with ligature I suppose. You can check typecast.com and see that when You insert fi it automatically is changed to if as You type.