While using tcolorboxes I found something strange. If the content of the box begins with the center-environment, minipage-environment or simply text, everything looks fine. But if the content begins with the math align-environment, there is a pretty big gap:
Normally it should look like this:
Can someone help me get rid of this gap? I have no idea, why this gap even exists. Here is a simple code example, if you want to play around with it:
\documentclass[a4paper, 11pt]{book}
\usepackage[most]{tcolorbox}
\tcbset{framedboxfilled/.style={ enhanced jigsaw,
sharp corners,
colback=white!80!gray,
colbacktitle=white!80!gray,
fonttitle={\bfseries},
coltitle=black,
toprule=1pt, titlerule=1pt, bottomrule=1pt,
leftrule=0pt, rightrule=0pt, right=0pt,
left=-2pt,
}
}
\tcbset{framedboxoutline/.style={%
framedboxfilled,
colback=white,
colbacktitle=white,
}
}
\def\myboxstyle{framedboxoutline}
\newtcolorbox[auto counter,number within=section]{beispiel}[2][]{%
\myboxstyle,
title={Beispiel \thetcbcounter~#2},
}
\begin{document}
\section{Test}
\begin{beispiel}{XOR-Operator}
\begin{align*}
&b1 && = && 1000\ 1000\ 1101\ 1001_2\\
&b2 && = && 1111\ 0000\ 1010\ 1101_2\\
&\text{result}\ b_1 \oplus b_2 && = && 0111\ 1000\ 0111\ 0100_2
\end{align*}
\end{beispiel}
\begin{beispiel}{Schlüssel einer Substitutions Cipher}
\begin{center}
\begin{tabular}{p{0pt}p{0pt}p{0pt}p{0pt}p{0pt}p{0pt}p{0pt}p{0pt}p{0pt}p{0pt}p{0pt}p{0pt}p{0pt}p{0pt}p{0pt}p{0pt}p{0pt}p{0pt}p{0pt}p{0pt}p{0pt}p{0pt}p{0pt}p{0pt}p{0pt}p{0pt}}
a & b & c & d & e & f & g & h & i & j & k & l & m & n & o & p & q & r & s & t & u & v & w & x & y & z\\
$\downarrow$ & $\downarrow$ & $\downarrow$ & $\downarrow$ & $\downarrow$ & $\downarrow$ & $\downarrow$ & $\downarrow$ & $\downarrow$ & $\downarrow$ & $\downarrow$ & $\downarrow$ & $\downarrow$ & $\downarrow$ & $\downarrow$ & $\downarrow$ & $\downarrow$ & $\downarrow$ & $\downarrow$ & $\downarrow$ & $\downarrow$ & $\downarrow$ & $\downarrow$ & $\downarrow$ & $\downarrow$ & $\downarrow$ \\
X &E &U &A &D &N &B &K &V &M &R &O &C &Q &F &S &Y &H &W &G &L &Z &I &J &P &T
\end{tabular}
\end{center}
\end{beispiel}
\end{document}
Best Answer
align*, being a vertical-mode environment, wants to introduce that vertical space between itself and what comes before it. A simple solution is to usealignedinstead, and place it inside centered, inline math, as in\centering$\begin{aligned}...\end{aligned}$.