flalign environment inside a tcolorbox

I've build a flalign environment and I'm happy with the result, but now I want to put it in a tcolorbox like in my example. I can't figure out how I can make that possible.

This is my MWE

\documentclass[preview]{standalone}
\usepackage{array,tabularx,calc}
\usepackage[dutch]{babel}
\usepackage{tcolorbox}
\tcbuselibrary{theorems}

\pagestyle{empty}

\definecolor{yourcolor}{RGB}{128, 0, 0}

\newlength{\conditionwd}
\newenvironment{conditions}[1][\\ \textbf{Waarin} \\\\]
{%
#1\tabularx{11cm}[t]{@{}
>{$}l<{$} @{${}={}$} X@{} >{[}>{$}r<{$}<{]}
}%
}
{\endtabularx\\belowdisplayskip]} \begin{document} \begin{tcolorbox}[ams align,colback=yellow!10!white,colframe=yourcolor] f(x) & = {} g(x) \end{tcolorbox} \begin{flalign} q_{as} = \frac{(m_{as} \cdot g)}{L_{ac}} && \end{flalign} \begin{conditions} q_{as} & Verdeelde belasting door de as & N \cdot mm\\ m_{as} & Massa van de aandrijfas & kg \\ g & gravitatieconstante & m/s^2 \end{conditions} \end{document}  which gives me this result; The tcolorbox(not overruling textwidth) is the one I want, but with the flalign and conditions in it. Is there someone who can help me out? Thank you in advance! 2 Answers Why not a single flalign for both equations? \documentclass[preview, border = 12pt]{standalone} \usepackage{array,tabularx,calc} \usepackage[dutch]{babel} \usepackage{tcolorbox} \tcbuselibrary{theorems} \pagestyle{empty} \definecolor{yourcolor}{RGB}{128, 0, 0} \newlength{\conditionwd} \newenvironment{conditions}[1][\\ \textbf{Waarin} \\\
{%
#1\tabularx{11cm}[t]{@{}
>{$}l<{$} @{${}={}$} X@{} >{[}>{$}r<{$}<{]}
}%
}
{\endtabularx\\[\belowdisplayskip]}

\begin{document}
\begin{tcolorbox}[colback=yellow!10!white,colframe=yourcolor]%
\begin{flalign}
& & f(x) & = {} g(x) & & \\
q_{as} = \frac{(m_{as} \cdot g)}{L_{ac}} &&
\end{flalign}
\begin{conditions}
q_{as} & Verdeelde belasting door de as & N \cdot mm\\
m_{as} & Massa van de aandrijfas & kg \\
g & gravitatieconstante & m/s^2
\end{conditions}
\end{tcolorbox}

\end{document}


Nice, thank you!

The first equation was only to show you a working tcolorbox example. When I built something like this:

\begin{tcolorbox}[ams align, colback=yellow!10!white,colframe=yourcolor]%
\begin{flalign}
q_{as} = \frac{(m_{as} \cdot g)}{L_{ac}} &&
\end{flalign}
\begin{conditions}
q_{as}  &   Verdeelde belasting door de as  &   N \cdot mm\\
m_{as}  &   Massa van de aandrijfas         & kg \\
g       &   gravitatieconstante             & m/s^2
\end{conditions}
\end{tcolorbox}


I get the error; !Argument of \flalign has an extra }.<inserted text>\par\end{tcolorbox}

But I see from your example that the problem was in the ams align of my tcolorbox. I don't know why that's forming a problem, but problem solved by removing it.

Thanks.

• This does not provide an answer to the question. To critique or request clarification from an author, leave a comment below their post. - From Review – Alessandro Cuttin Jul 19 at 9:40
• @AlessandroCuttin It seems to be an answer: Removing ams align. Though I agree, it looks like a response to the other answer. – Stefan Kottwitz Jul 19 at 10:34
• @StefanKottwitz then it can be kept as a self-answer (sort of) – Alessandro Cuttin Jul 19 at 13:04