chapter style with tcolorbox?

Question

Is it possible to customize chapter style like below picture by using tcolorbox package? if not, can you show me which package could generate that such style? Thanks

Answer 1

Here's one possibility using tcolorbox and titlesec. An image for an unnumbered chapter:

An image for a numbered chapter:

The code:

\documentclass{book}
\usepackage[explicit]{titlesec}
\usepackage[many]{tcolorbox}
\usepackage{lmodern}
\usepackage{lipsum}

\definecolor{titlebgdark}{RGB}{0,163,243}
\definecolor{titlebglight}{RGB}{191,233,251}

\titleformat{\chapter}[display]
  {\normalfont\huge\bfseries}
  {}
  {20pt}
  {%
    \begin{tcolorbox}[
      enhanced,
      colback=titlebgdark,
      boxrule=0.25cm,
      colframe=titlebglight,
      arc=0pt,
      outer arc=0pt,
      leftrule=0pt,
      rightrule=0pt,
      fontupper=\color{white}\sffamily\bfseries\huge,
      enlarge left by=-1in-\hoffset-\oddsidemargin, 
      enlarge right by=-\paperwidth+1in+\hoffset+\oddsidemargin+\textwidth,
      width=\paperwidth, 
      left=1in+\hoffset+\oddsidemargin, 
      right=\paperwidth-1in-\hoffset-\oddsidemargin-\textwidth,
      top=0.6cm, 
      bottom=0.6cm,
      overlay={
        \node[
          fill=titlebgdark,
          draw=titlebglight,
          line width=0.15cm,
          inner sep=0pt,
          text width=1.7cm,
          minimum height=1.7cm,
          align=center,
          font=\color{white}\sffamily\bfseries\fontsize{30}{36}\selectfont
        ] 
        (chapname)
        at ([xshift=-4cm]frame.north east)
        {\thechapter};
        \node[font=\small,anchor=south,inner sep=2pt] at (chapname.north)
        {\MakeUppercase\chaptertitlename};  % if using amsbook, this should be \chaptername
      } 
    ]
    #1
    \end{tcolorbox}%
  }
\titleformat{name=\chapter,numberless}[display]
  {\normalfont\huge\bfseries}
  {}
  {20pt}
  {%
    \begin{tcolorbox}[
      enhanced,
      colback=titlebgdark,
      boxrule=0.25cm,
      colframe=titlebglight,
      arc=0pt,
      outer arc=0pt,
      remember as=title,
      leftrule=0pt,
      rightrule=0pt,
      fontupper=\color{white}\sffamily\bfseries\huge,
      enlarge left by=-1in-\hoffset-\oddsidemargin, 
      enlarge right by=-\paperwidth+1in+\hoffset+\oddsidemargin+\textwidth,
      width=\paperwidth, 
      left=1in+\hoffset+\oddsidemargin, 
      right=\paperwidth-1in-\hoffset-\oddsidemargin-\textwidth,
      top=0.6cm, 
      bottom=0.6cm, 
    ]
    #1
    \end{tcolorbox}%
  }
\titlespacing*{\chapter}
  {0pt}{0pt}{40pt}
\makeatother

\begin{document}

\chapter*{A test unnumbered chapter}
\lipsum[4]
\chapter{A test chapter with a long title that will span more than one line}
\lipsum[4]

\end{document}