Thread:Project:Support desk/Span tags visible

Hi - version 1.16.3 I am having trouble with the span tag, which is mysteriously becoming visible. E.g. should create invisible anchor but doesn't.  This does not happen on Wikipedia, must be my Wiki. Example page is here http://www.logicmuseum.com/wiki/User:Edward_Ockham/Test_page

Grateful for any help.