+\renewcommand{\vec}[1]{{\bm #1{}}}
+
+%
+% theorem environment
+%
+% common
+\theoremstyle{plain}
+\theoremseparator{:}
+\theorembodyfont{\normalfont}
+\theoremsymbol{}
+% theorem
+\shadecolor{ctheorem}
+\newshadedtheorem{theorem}{Theorem}[section]
+% definition
+\shadecolor{cdefinition}
+\newshadedtheorem{definition}[theorem]{Definition}
+% remark
+\shadecolor{cremark}
+\newshadedtheorem{remark}[theorem]{Remark}
+% proof
+\theoremstyle{nonumberplain}
+\theoremsymbol{\rule{1ex}{1ex}}
+\shadecolor{cproof}
+\newtheorem{proof}{Proof}