Truly center block of text and equations on a flashcard

Question

So I am trying to create a series of small flashcards A6 size as follows

\documentclass{article}
\usepackage[norsk]{babel}%
\usepackage[a6paper, landscape, left=10mm, right=10mm]{geometry}% http://ctan.org/pkg/geometry
% ============================================================
% v OWN COMMANDS AND PACKAGES BELOW HERE v
% ============================================================
\usepackage{amssymb}
\usepackage{mathtools}
\usepackage{enumitem}
\usepackage{multicol}
\setlist[enumerate,1]{label={\arabic*)}}
\usepackage{xcolor}
\definecolor{mengder}{HTML}{093145}
% https://tex.stackexchange.com/questions/7355/how-to-suppress-page-number
\pagenumbering{gobble} %
\begin{document}
\Huge
%==============================================================================%
%                                Mengder                                %
%==============================================================================%
\pagecolor{mengder}
\color{white}
% \setfpvar{angle.p8}{10+5\randomint{3}{11}}
%\setfpvar{angle.p8}{40 + 5\randomint{0}{4}} % random.randrange(40,60,5)
\include{Q1-mengder-utsagn}
\include{Q2-mengder-SnittOgUnion}
\include{Q3-mengder-listeform}
\nopagecolor
\end{document}

Where my flashcards are defined as follows

Q1-mengder-utsagn.tex

La $\{3, 5, 7\}$ og $B = \{3, 7\}$ \bigskip
Hvilke utsagn er sanne? \bigskip
\begin{center}
    \begin{multicols}{2}
        \begin{enumerate}[label={$\square$}]
            \item $3 \in B$
            \item $0 \in A$
            \item $A \subset B$
            \item $5, 7 \in A$
            \item $B \subset A$
            \item $10 \not \in A$
        \end{enumerate}
    \end{multicols}
\end{center}

Q2-mengder-SnittOgUnion.tex

La $R = \{2,5,7,11\}$ \\ \phantom{S}\! og $S = \{5,7,11,15\}$
\bigskip
Finn\bigskip
\begin{center}
    \begin{multicols}{2}
        \begin{enumerate}[label={$\square$}]
            \item $R \cap S$
            \item $R \cup S$
            \item $R \setminus S$
            \item $S \setminus R$
        \end{enumerate}
    \end{multicols}
\end{center}

Q3-mengder-listeform.tex

Gitt $M=\{6,7,8,9,10,11,12\}$. \\
\bigskip
Finn
\bigskip
\begin{center}
    \begin{enumerate}
        \item \mbox{$A = { x \in M \mid x \neq 7, x \neq 10}$}
        \item $A = { x + 7 \mid x \in M}$
    \end{enumerate}
\end{center}

The output now looks like

Where I would expect a centered output, to look more like

E.G the widest part of the textblock is equally far away from the margins. Similar is true for the top and bottom part of the textblock. Is there a non-manual way to acheive this? (I need around a hundred of these cards).

I also have tried to following the advice given here, center horizontally and vertically a block of text. Without much success. Eg rewriting

Q1-mengder-utsagn.tex

as

\vspace*{\fill}
\begin{list}{}{%
  \leftmargin=0pt
  \rightmargin=0pt
  \listparindent=\parindent
  \itemindent=\parindent
  \itemsep=0pt
  \parsep=0pt}
\item\relax
La ${3, 5, 7}$ og $B = {3, 7}$ \bigskip
Hvilke utsagn er sanne? \bigskip
\begin{center}
    \begin{multicols}{2}
        \begin{enumerate}[label={$\square$}]
            \item $3 \in B$
            \item $0 \in A$
            \item $A \subset B$
            \item $5, 7 \in A$
            \item $B \subset A$
            \item $10 \not \in A$
        \end{enumerate}
    \end{multicols}
\end{center}
\end{list}
\vfill % equivalent to \vspace{\fill}

gives

which clearly is not centered either. What am I doing wrong? I have tried adding minipages and centerings without much success.

I would use a tabular instead of enumerate. Enumerate uses the whole column whether it needs it or not. Tabular usually shrinks to fit the largest entry in each column (just don't use p{] columns). — John Kormylo, Nov 19 '21 at 01:43

Simon Dispa · Accepted Answer · 2021-11-19T14:42:51.637

UPDATE

(1) Center the text area in the page setting the margins with geometry

(2) Inside the flashcards, center the content vertically.

This solution defines the environment CenterCard with three parameters:

Contents of the top of the flashcard;
Elements to be displayed at the bottom, up to three elements per line. Each line has the form item1 & item2 \\ or just item1 \\;
Symbols to insert before each elements. A counter is provided to simulate the environment enumerate.

CenterCard uses the environment varwidth, similar to minipage but with a resulting width of the natural width of its contents; and a tabular environment to present the elements in columns.

\documentclass{article}
\usepackage[norsk]{babel}%
\usepackage[a6paper,
landscape, 
left=10mm,
right=10mm,
marginparsep=0pt, 
marginparwidth=0pt,
vmargin=9mm, % save space  for printing
ignoreheadfoot,
]{geometry}% changed <<<<
\setlength{\topskip}{0pt} % added  <<<<
% ============================================================
% v OWN COMMANDS AND PACKAGES BELOW HERE v
% ============================================================
\usepackage{caption,booktabs,array}
\usepackage{amssymb}
\usepackage{mathtools}
%\usepackage{enumitem} % not used
%\usepackage{multicol}  % not used
\usepackage{varwidth}% added <<<<<<<<<<<<<<<<<<<<<<<<<
\usepackage{xcolor}
\definecolor{mengder}{HTML}{093145}
\usepackage{showframe} % show the margins <<<<<<<<
\renewcommand*\ShowFrameColor{\color{red}}
% https://tex.stackexchange.com/questions/7355/how-to-suppress-page-number
\pagenumbering{gobble} %
\newcounter{CellNumber}% to add numbers to the cells
\newenvironment{CenterCard}[3]{%
\parindent0pt
\setcounter{CellNumber}{0}
\pagecolor{mengder}
\color{white}\Huge
\vspace{\fill}\nointerlineskip
\begin{center}\begin{varwidth}{\textwidth} #1\end{varwidth}\end{center}\bigskip%
\begin{center}
    \begin{varwidth}{\textwidth}
        \setlength{\tabcolsep}{30pt}% separation of the columns <<<<<<<<<<<<<<<<<<<<<
        \setlength{\extrarowheight}{5pt}% extra row separation <<<
        \begin{tabular}{{3}{>{#3}l}}
            #2}
        {%
        \end{tabular}\setcounter{CellNumber}{0}
    \end{varwidth}
\end{center}
\vfill \clearpage}
\begin{document}
%%

%%      %==============================================================================%
%%      %                                Mengder                                %
%%      %==============================================================================%
%%

\begin{CenterCard}
    {La ${3, 5, 7}$ og $B = {3, 7}$ \bigskip
Hvilke utsagn er sanne? \bigskip}
{%
$3 \in B$ &amp;$5, 7 \in A$ \\
$0 \in A$ &amp; $A \subset B$ \\    
$B \subset A$ &amp; $10 \not \in A$}        
{$\square$\enspace}

\end{CenterCard}
\begin{CenterCard}
    {La $R = {2,5,7,11}$ \  og $S = {5,7,11,15}$

    \bigskip
Finn\bigskip}
{%
$R \cap S$ &amp; $R \setminus S$ \\
$R \cup S$  &amp; $S \setminus R$
}       
{$\square$\enspace}

\end{CenterCard}
\begin{CenterCard}
    {Gitt $M={6,7,8,9,10,11,12}$. \

    \bigskip
Finn    
\bigskip}
{%
\mbox{$A = \{ x \in M \mid x \neq 7, x \neq 10\}$}  \\  
 $A = \{ x + 7 \mid x \in M\}$
}
{\stepcounter{CellNumber}\theCellNumber)\enspace}

\end{CenterCard}
\end{document}

@N3buchadnezzar This is the only requirement left? I thought that the problem was centering. — Simon Dispa, Nov 19 '21 at 00:13
@N3buchadnezzar I will update the answer. Any solution depends on the templates you have for the cards. So far there are two different. Do you have more? — Simon Dispa, Nov 19 '21 at 13:01

Truly center block of text and equations on a flashcard

1 Answers1