< that is not in HTML source code appears when loading page on the web

For the life of me, I cannot figure out how this < (which is the code for the bracket <) appears on my pure HTML page when loading it on the web. It appears both in Firefox and Chrome:

screenshot 1

The < code is NOT there when I upload the page or check the source code directly on the server with my FTP client:

screenshot 2

I cannot see the < when displaying the source code of the entire page on the web either. I can only see it when selecting the text in the area and then"showing selection source":

screenshot 3

Is this some sort of browser bug that affects both Firefox and Chrome? I cannot think of any other explanation.

The page: http://www.weltsprachen.net/ukrainisch-lernprogramme.html (in German). Other pages on the same website with almost exactly the same code do not have this problem.