simplified rail setup, using plain defaults (NB: \small is incompatible with \isabellestyle used here);
1 %% rail antiquotation environment
2 \newenvironment{railoutput}%
3 {\begin{list}{}{\rail@param}\def\rail@expand{\relax}\makeatletter}{\end{list}}
6 \def\rail@termfont{\isabellestyle{tt}}
7 \def\rail@nontfont{\isabellestyle{it}}
8 \def\rail@namefont{\isabellestyle{it}}