Rendering issue with tikz-cd package and gtpart.cls document class

Question

I need to make some fairly complicated commutative diagrams for a math paper, but for some reason, my installation of TeXShop is having trouble rendering even a simple diagram. Here is a minimal working example for the bad behavior:

\documentclass{gtpart}


\usepackage{tikz-cd}


\begin{document}

Examples from the \{tikzcd\} manual, section 1.2.

Example 1:

\begin{tikzcd}
A \arrow[rd] \arrow[r, "\phi"] & B \\
& C
\end{tikzcd}

Example 2: 

\begin{tikzcd}
A \arrow[r, "\phi"] \arrow[d, red]
& B \arrow[d, "\psi" red] \\
C \arrow[r, red, "\eta" blue]
& D
\end{tikzcd}

Example 4:

\begin{tikzcd}
T
\arrow[drr, bend left, "x"]
\arrow[ddr, bend right, "y"]
\arrow[dr, dotted, "{(x,y)}" description] & & \\
& X \times_Z Y \arrow[r, "p"] \arrow[d, "q"]
& X \arrow[d, "f"] \\
& Y \arrow[r, "g"]
& Z
\end{tikzcd}

\end{document}

And here is the output in the PDF document:

As you can see, this is hardly what I'd like to have appear in the paper, and for more complex diagrams it just gets worse! I have uninstalled all LaTeX distributions and reinstalled MacTeX twice (all 4.6GB of it), and I still get this type of rendering. I'm running a MacBook Pro on OS X 10.7.5. Anyone know what might be going on here? Let me know what else I can provide for someone to help me out! I'd really love to have tikz-cd working since it seems to be a great package for complex commutative diagrams.

NOTES: After creating the minimal working example, it appears this issue is a conflict with the tag \documentclass{gtpart}; when I use \documentclass{article}, the diagrams render properly. Here is a link to the gtpart.cls file.

Thanks to everyone who takes a look at this!

Answer 1

The primitive TeX parameter mathsurround is almost never changed, and tikz-cd clearly isn't expecting it to change but that class sets it to .8pt Setting it back to 0 seems simplest. (You could do it locally just around the tikz-cd)

\documentclass{gtpart}


\usepackage{tikz-cd}

\setlength\mathsurround{0pt}%<<<<<<<<<<<<<<<<<<<<<<<<


\begin{document}

Examples from the \{tikzcd\} manual, section 1.2.

Example 1:

\begin{tikzcd}
A \arrow[rd] \arrow[r, "\phi"] & B \\
& C
\end{tikzcd}

Example 2: 

\begin{tikzcd}
A \arrow[r, "\phi"] \arrow[d, red]
& B \arrow[d, "\psi" red] \\
C \arrow[r, red, "\eta" blue]
& D
\end{tikzcd}

Example 4:

\begin{tikzcd}
T
\arrow[drr, bend left, "x"]
\arrow[ddr, bend right, "y"]
\arrow[dr, dotted, "{(x,y)}" description] & & \\
& X \times_Z Y \arrow[r, "p"] \arrow[d, "q"]
& X \arrow[d, "f"] \\
& Y \arrow[r, "g"]
& Z
\end{tikzcd}

\end{document}