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I would like to colorize my theorems and questions. I use the following code:

\documentclass{amsart}
\usepackage[dvipsnames]{xcolor}
\usepackage[breaklinks,colorlinks,pagebackref]{hyperref} 
\hypersetup{linkcolor=Red , citecolor=Green}
\usepackage[capitalise,nameinlink]{cleveref}
\newtheorem{theorem}{\color{Blue} Theorem}[section]
\theoremstyle{definition}
\newtheorem{question}[theorem]{\color{Blue} Question }
\begin{document}
\begin{question}\label{qu1}  Question 1
\end{question}

\begin{theorem}\label{thm1} Theorem 1
\end{theorem}
Now we reference to ~\cref{thm1} and ~\cref{qu1}.

\end{document}

By running this, I get the following Error massage:

Argument of \@declaredcolor has an extra }."

I don't know what the problem is. Can you see the problem?

Thanks

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  • Please advise whether the color Blue should apply to just the environment's "label" ("Theorem", "Question", etc) or to the associated numbers ("0.1", "0.2", etc) as well. Commented Apr 18, 2018 at 1:06

2 Answers 2

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3

\color is a "fragile" (in the LaTeX-specific sense of the word) command. You need to change

\newtheorem{theorem}{\color{Blue} Theorem}[section]
\theoremstyle{definition}
\newtheorem{question}[theorem]{\color{Blue} Question }

to

\newtheorem{theorem}{\protect\color{Blue} Theorem}[section]
\theoremstyle{definition}
\newtheorem{question}[theorem]{\protect\color{Blue} Question }

Even better though, as shown in egreg's answer, is to (re)run \crefname on the theorem and question counters. Here's an MWE (minimum working example):

enter image description here

\documentclass{amsart} % loads 'amsthm' package automatically

\usepackage[dvipsnames]{xcolor}
\usepackage[colorlinks,linkcolor=Red]{hyperref} 
\usepackage[capitalise,nameinlink]{cleveref}

\newtheorem{theorem}{\color{Blue}Theorem}[section]
\theoremstyle{definition}
\newtheorem{question}[theorem]{\color{Blue}Question}
\crefname{theorem}{Theorem}{Theorems} % thanks, @egreg!
\crefname{question}{Question}{Questions}

\begin{document}
\setcounter{section}{2} % just for this example

\begin{question}\label{qu1}Question 1\end{question}
\begin{theorem}\label{thm1}Theorem 1\end{theorem}
\noindent
Now we cross-reference~\cref{thm1,qu1}.
\end{document}
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6
  • 1
    @MOB Mico is very excellent user. He will surely solve your problem. Commented Apr 17, 2018 at 22:20
  • Dear @Mico: Thanks for you answer. I have added \protect. But when I run it the Question will be in Blue and the link to it is also in Blue. But the linkcolor=Red is not Blue. Can you see the problem? Commented Apr 17, 2018 at 22:23
  • Yes, it compiles fine, but doesn't do what's expected. Besides, \textcolor is the right command instead of \color. Commented Apr 17, 2018 at 22:45
  • @egreg - with \textcolor, only the "label" ("Theorem", "Question", etc) gets colorized, but not the associated number. That's why I kept the OP's \color directive (while adding \protect). However, your solution (run \crefname) does away with the need for \protection. Commented Apr 18, 2018 at 5:35
  • @MOB - I've updated my answer. Commented Apr 18, 2018 at 5:42
4

You have to remove the color specification for \cref:

\documentclass{amsart}
\usepackage[dvipsnames]{xcolor}
\usepackage[colorlinks,pagebackref]{hyperref} 
\usepackage[capitalise,nameinlink]{cleveref}

\hypersetup{linkcolor=Red , citecolor=Green}

\newtheorem{theorem}{\textcolor{Blue}{Theorem}}[section]
\theoremstyle{definition}
\newtheorem{question}[theorem]{\textcolor{Blue}{Question}}

\crefname{theorem}{Theorem}{Theorems}
\crefname{question}{Question}{Questions}

\begin{document}

\begin{question}\label{qu1}
Question 1
\end{question}

\begin{theorem}\label{thm1}
Theorem 1
\end{theorem}

Now we reference to~\cref{thm1} and~\cref{qu1}.

\end{document}

enter image description here

OK, this doesn't color the number. Since Mico stole my code, here's a better one.

\documentclass{amsart}
\usepackage[dvipsnames]{xcolor}
\usepackage[colorlinks,pagebackref]{hyperref} 
\usepackage[capitalise,nameinlink]{cleveref}

\hypersetup{linkcolor=Red , citecolor=Green}

% see https://tex.stackexchange.com/a/17555/4427
\newtheoremstyle{colorplain}
  {\topsep}   % ABOVESPACE
  {\topsep}   % BELOWSPACE
  {\itshape}  % BODYFONT
  {0pt}       % INDENT (empty value is the same as 0pt)
  {\color{Blue}\bfseries} % HEADFONT
  {.}         % HEADPUNCT
  {5pt plus 1pt minus 1pt} % HEADSPACE
  {}          % CUSTOM-HEAD-SPEC
\newtheoremstyle{colordefinition}
  {\topsep}   % ABOVESPACE
  {\topsep}   % BELOWSPACE
  {\normalfont}  % BODYFONT
  {0pt}       % INDENT (empty value is the same as 0pt)
  {\color{Blue}\bfseries} % HEADFONT
  {.}         % HEADPUNCT
  {5pt plus 1pt minus 1pt} % HEADSPACE
  {}          % CUSTOM-HEAD-SPEC

\theoremstyle{colorplain}
\newtheorem{theorem}{Theorem}[section]
\theoremstyle{colordefinition}
\newtheorem{question}[theorem]{Question}

\begin{document}

\begin{question}\label{qu1}
Question 1
\end{question}

\begin{theorem}\label{thm1}
Theorem 1
\end{theorem}

Now we reference to~\cref{thm1} and~\cref{qu1}.

\end{document}

enter image description here

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  • Now I am very fast to upvote also for you :-). Commented Apr 17, 2018 at 22:44

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