Uses variable-width font for pre

[GyrosGeier]

With the theme enabled, HTML pre elements start using a variable-width font, unless they match a more specific rule such as pre.console-output.

The stdout/stderr view for jUnit testcases uses a <pre>…</pre> block without a class name to format the output, expecting a fixed-width font. This still works with the base theme, as it does not override the default font choice for pre, but in the Neo theme, "Open Sans" is used instead.