Tcolorbox, titlerule or attach boxed title ruins transparency of the title

tcolorbox

Based on this answer I tried to get a transparent tcolorbox but I'd like to have a titlerule

I notice that when I add the line

the upperbox is not transparent, attach boxed title to top left
the full box appears titlerule style={red,arrows = {Hooks[arc=270]-Hooks[arc=270]}} ]

There must be a reason and I am certainly missing something.

MWE

\documentclass[tikz]{article}
\usepackage{xcolor}
\usepackage{pagecolor}
\pagecolor{yellow}
\usepackage[most]{tcolorbox}
\usetikzlibrary{arrows.meta}
\begin{document}
\begin{tcolorbox}[
%    standard jigsaw,
    enhanced,    
    title=Title,
    coltitle = red,
%    titlerule style={red,arrows = {Hooks[arc=270]-Hooks[arc=270]}} ] <= I'd like it to be transparent
%    attach boxed title to top left, % <= I'd like it to be transparent
     opacityframe=0,    
    opacityback=0,  
    opacitybacktitle=0,
]
This should have transparent backround. \\
Background should look yellow. 
\end{tcolorbox}
\end{document}

Best Answer

With boxed titles, title style is independent of tcolorbox style, then you have to repeat opacity options into boxed title style.

In general the frame is not a line but a filled box over which the colback box is added. This is the reason why with opacityback=0 the resulting box shows darker because the frame is still visible.

\documentclass[tikz]{article}
\usepackage{xcolor}
\usepackage{pagecolor}
\pagecolor{yellow}
\usepackage[most]{tcolorbox}
\usetikzlibrary{arrows.meta}
\begin{document}
\begin{tcolorbox}[
%    standard jigsaw,
    enhanced,    
    title=Title,
    coltitle = red,
%    titlerule style={red,arrows = {Hooks[arc=270]-Hooks[arc=270]}}, % <= I'd like it to be transparent
%    attach boxed title to top left, % <= I'd like it to be transparent
     opacityframe=0,    
    opacityback=0,  
    opacitybacktitle=0,
]
This should have transparent backround. \\
Background should look yellow. 
\end{tcolorbox}

\begin{tcolorbox}[
%    standard jigsaw,
    enhanced,    
    title=Title,
    coltitle = red,
%    titlerule style={red,arrows = {Hooks[arc=270]-Hooks[arc=270]}}, %  <= I'd like it to be transparent
    attach boxed title to top left, % <= I'd like it to be transparent
     opacityframe=0,    
    opacityback=0,  
    opacitybacktitle=0,
    boxed title style={opacityframe=0, opacityback=0}
]
This should have transparent backround. \\
Background should look yellow. 
\end{tcolorbox}

\begin{tcolorbox}[
%    standard jigsaw,
    enhanced,    
    title=Title,
    coltitle = red,
    titlerule style={red,arrows = {Hooks[arc=270]-Hooks[arc=270]}}, % <= I'd like it to be transparent
    %attach boxed title to top left, % <= I'd like it to be transparent
    opacityframe=0,    
    opacityback=0,  
%   opacitybacktitle=0,
%   boxed title style={opacityframe=0, opacityback=0}
]
This should have transparent backround. \\
Background should look yellow. 
\end{tcolorbox}
\end{document}

Related Solutions

[Tex/LaTex] Tcolorbox: same boxed title style after break

This uses a 'tricky' overlay approach, setting explicitly another tcolorbox as the box title for the broken parts of the box.

The extras middle and last= option is meant to add features to the 'middle' and 'last' box parts, i.e. the ones after breaking the box.

\documentclass{article}
\usepackage{lipsum}%
\usepackage[all]{tcolorbox}%

\begin{document}

\def\TheTitle{Boxed title}



\tcbset{boxtitlestuff/.style={boxrule=0.4pt,colback=black!2!white,coltitle=black,fonttitle={\bfseries},size=normal},
        brokentitle/.style={geometry nodes=true,skin=freelancemiddle,
          extras middle and last={overlay={\node[above,inner sep=-4pt] (A) at (interior.north) {\tcbox[boxtitlestuff]{continued \TheTitle}};}
          }
        }
      }


\begin{tcolorbox}[skin=enhanced jigsaw,
  breakable,
  attach boxed title to top center={yshift=-2mm},
  coltitle=black,
  boxed title style={boxrule=0.4pt,colback=black!2!white},
  title=\TheTitle,
%  title after break={continued \TheTitle},
  brokentitle
  ]
\lipsum
\lipsum
\lipsum
\lipsum
\end{tcolorbox}

\end{document}

[Tex/LaTex] Environment with amsthm and tcolorbox – Attach boxed title to top

Never mix ntheorem or amsthm and tcbtheorem. Rather use only one of them and separate their definitions.
If i understand you correctly, you look for something like this:

Title (text beside "Theorem" or "Definition") is obligatory field, so if you not like to have this text, leave it empty. for example: \begin{YetAnotherTheorem}{}{mittelwertsatz_n4}.

Above image is generated by:

\documentclass{scrbook}
\usepackage[english]{babel}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{amsthm}
\usepackage{xcolor}
\usepackage{tcolorbox}
\tcbuselibrary{many}
\usepackage{varwidth}

%Theorem with tcolorbox
\newtcbtheorem{YetAnotherTheorem}{Theorem}%
{
    enhanced jigsaw, breakable,
    frame empty, interior empty,
    colframe=green!50!white, coltitle=green!50!black,
    fonttitle=\bfseries,colbacktitle=green!15!white,
    borderline={1mm}{0mm}{green},
    attach boxed title to top center={yshift=-2mm},
    boxed title style={boxrule=0.4pt},
    varwidth boxed title
}{theo}

\newtcbtheorem{definition}{Definition}%
{
    enhanced jigsaw, breakable,
    colframe=blue,colback=blue!20!white,
    breakable,
    before skip=10pt,after skip=10pt,
    attach boxed title to top center={yshift=-2mm}
}{def}

\begin{document}
\begin{YetAnotherTheorem}{Mittelwertsatz f\"{u}r $n$ Variable}{mittelwertsatz_n4}
    Es sei $n\in\mathbb{N}$, $D\subseteq\mathbb{R}^n$ eine offene Menge und
    $f\in C^{1}(D,\mathbb{R})$. Dann gibt es auf jeder Strecke
    $[x_0,x]\subset D$ einen Punkt $\xi\in[x_0,x]$, so dass gilt
\[
f(x)-f(x_0) = \operatorname{grad} f(\xi)^{\top}(x-x_0)
\]
\end{YetAnotherTheorem}

\begin{YetAnotherTheorem}{}{mittelwertsatz_n4}
    Es sei $n\in\mathbb{N}$, $D\subseteq\mathbb{R}^n$ eine offene Menge und
    $f\in C^{1}(D,\mathbb{R})$. Dann gibt es auf jeder Strecke
    $[x_0,x]\subset D$ einen Punkt $\xi\in[x_0,x]$, so dass gilt
\[
f(x)-f(x_0) = \operatorname{grad} f(\xi)^{\top}(x-x_0)
\]
\end{YetAnotherTheorem}

\begin{definition}{}{important-definition}
    Eine Funktion $f:~I\to\mathbb{R}$ auf einem Intervall $I$ hei\ss{}t in $x_0\in I$ differenzierbar oder linear approximierbar, wenn der Grenzwert
\[
\lim\limits_{x\to x_0}\frac{f(x)-f(x_0)}{x-x_0}=\lim\limits_{h\to 0}\frac{f(x_0+h)-f(x_0)}{h}
\]
    existiert. Bei Existenz hei\ss{}t dieser Grenzwert Ableitung oder Differentialquotient von $f$ in $x_0$ und man schreibt f\"{u}r ihn
\[
f’(x_0)\quad\text{oder}\quad\frac{df}{dx}(x_0).
\]
\end{definition}
\end{document}

Best Answer

Related Solutions

[Tex/LaTex] Tcolorbox: same boxed title style after break

[Tex/LaTex] Environment with amsthm and tcolorbox – Attach boxed title to top

Related Question