I was trying to create a custom abstract environment with minipages and adjusted margins. Everything works fine, except for that the right margin changes according to the left. I could'n find solution. Here is the whole code:
\documentclass{article}
\usepackage[a4paper]{geometry}
% Setting character encoding to UFT-8, and loading the babel package
% with Hungarian language.
\usepackage[utf8]{inputenc}
\usepackage[magyar]{babel}
\usepackage[T1]{fontenc}
\usepackage{lipsum}
\usepackage{multicol}
\usepackage{changepage}
\author{Alap Tibor}
\title{\LaTeX\ gyakorlás}
\newenvironment{myabstract}
{\begin{adjustwidth}{-1cm}{-1cm}
\begin{minipage}{0.3\textwidth}
\vspace{-1cm}
\maketitle
\end{minipage}
\begin{minipage}{0.7\textwidth}
\begin{flushleft}
\textbf{\textit{ABSTRACT}}
\end{flushleft}
\vspace{2mm}
\hrule %{\textwidth}{1.5pt}
\smallskip
\textbf\bgroup}
{\egroup
\vspace{1mm}
\hrule %{\textwidth}{1.5pt}
\end{minipage}
\end{adjustwidth}
\vspace{1cm}}
\begin{document}
\begin{myabstract}
\lipsum[13]
\end{myabstract}
\begin{multicols}{2}
\section{Bevezető}
\lipsum[22-24]
\end{multicols}
\end{document}
Adjusting the second parameter of \adjustwidth does not make any change.
Many thanks for any advice.

myabstract's definition inside aminipage? – Werner Dec 10 '13 at 22:47