% enlarge text width by eliminating extra margins.
% use this AFTER a4 document substyle
\makeatletter{}
% A4 paper width = 21cm
\setlength{\textwidth}{21 true cm}		% A4 paper width
\addtolength{\textwidth}{-2 true in}		% allow for printer margins
\setlength{\marginparsep}{10pt}			% 10pt from text
\setlength{\marginparwidth}{1 true in}		% margin width
\addtolength{\marginparwidth}{-.25in}		% not too close to edge
\addtolength{\marginparwidth}{-\marginparsep}	% or to text
\setlength{\oddsidemargin}{0 true in}
\setlength{\evensidemargin}{0 true in}
\makeatother{}