When I was viewing specfile in b.o.o web UI,
body > content > package_tabs > CodeMirror > CodeMirror-scrollcm-s-default
has a style "height: 8px;" which is not accute. (maybe it's test code which is forgotten to remove)
it'll limit the specfile viewer, cauing you can't see any characters.
remove it then everything will be okay.
this is firefox 17.0.1 (the one in M2), chromium is okay to do that.
Hope it helps