对代码稍作修改后发现这里由 Gonzalo Medina 开发，如何保持章节和子章节编号左对齐，同时仍保留彩色框和线条？效果如下：
以下是针对章节编号的边距调整的修改后的代码：
\documentclass[11pt,fleqn]{book}
\usepackage[english]{babel}
\usepackage{lipsum}
\usepackage{xcolor}
\usepackage{tikz}
\usepackage{mathtools,amsfonts,amssymb,amsthm}
\usepackage[most]{tcolorbox}
\definecolor{ocre}{RGB}{52,177,201}
\definecolor{ultramarine}{RGB}{0,45,97}
\definecolor{mybluei}{RGB}{0,173,239}
\definecolor{myblueii}{RGB}{63,200,244}
\definecolor{myblueiii}{RGB}{199,234,253}
\usepackage{fourier}
\usepackage[explicit,calcwidth]{titlesec}
\renewcommand\thechapter{\arabic{chapter}}
\newcommand\chapnumfont{%
\fontsize{380}{130}\color{myblueii}\selectfont%
}
\newcommand\chapnamefont{%
\normalfont\color{white}\scshape\small\bfseries
}
\titleformat{\chapter}
{\normalfont\huge\filleft}
{}
{0pt}
{\stepcounter{chapshift}%
\begin{tikzpicture}[remember picture,overlay]
\fill[myblueiii]
(current page.north west) rectangle ([yshift=-13cm]current page.north east);
\node[
fill=mybluei,
text width=2\paperwidth,
rounded corners=6cm,
text depth=18cm,
anchor=center,
inner sep=0pt] at (current page.north east) (chaptop)
{\thechapter};%
\node[
anchor=south east,
inner sep=0pt,
outer sep=0pt] (chapnum) at ([xshift=-20pt]chaptop.south)
{\chapnumfont\thechapter};
\node[
anchor=south,
inner sep=0pt] (chapname) at ([yshift=2pt]chapnum.south)
{};
\node[
anchor=north east,
align=right,
inner xsep=0pt] at ([yshift=-0.5cm]chapname.east|-chapnum.south)
{\parbox{.7\textwidth}{\raggedleft#1}};
\end{tikzpicture}%
}
\titleformat{name=\chapter,numberless}
{\normalfont\huge\filleft}
{}
{0pt}
{\begin{tikzpicture}[remember picture,overlay]
\fill[myblueiii]
(current page.north west) rectangle ([yshift=-13cm]current page.north east);
\node[
fill=mybluei,
text width=2\paperwidth,
rounded corners=6cm,
text depth=18cm,
anchor=center,
inner sep=0pt] at (current page.north east) (chaptop)
{};%
\node[
anchor=south east,minimum width=2in,
inner sep=0pt,
outer sep=0pt] (chapnum) at ([xshift=-20pt]chaptop.south)
{};
\node[
anchor=south,
inner sep=0pt] (chapname) at ([yshift=2pt]chapnum.south)
{};
\node[
anchor=north east,
align=right,
inner xsep=0pt] at ([yshift=-0.5cm]chapname.east|-chapnum.south)
{\parbox{.7\textwidth}{\raggedleft#1}};
\end{tikzpicture}%
}
\titlespacing*{\chapter}{0pt}{0pt}{3.5in}
\titlespacing*{name=\chapter,numberless}{0pt}{0pt}{3.5in}
\makeatletter
\renewcommand{\@seccntformat}[1]{\llap{\textcolor{ocre}{\csname the#1\endcsname}\hspace{1em}}}
\renewcommand{\section}{\@startsection{section}{1}{\z@}
{-4ex \@plus -1ex \@minus -.4ex}
{1ex \@plus.2ex }
{\normalfont\large\sffamily\bfseries}}
\renewcommand{\subsection}{\@startsection {subsection}{2}{\z@}
{-3ex \@plus -0.1ex \@minus -.4ex}
{0.5ex \@plus.2ex }
{\normalfont\sffamily\bfseries}}
\renewcommand{\subsubsection}{\@startsection {subsubsection}{3}{\z@}
{-2ex \@plus -0.1ex \@minus -.2ex}
{.2ex \@plus.2ex }
{\normalfont\small\sffamily\bfseries}}
\renewcommand\paragraph{\@startsection{paragraph}{4}{\z@}
{-2ex \@plus-.2ex \@minus .2ex}
{.1ex}
{\normalfont\small\sffamily\bfseries}}
%\titleformat{\section}
% {\addtolength{\titlewidth}{4pc}\normalfont\Large\sffamily\bfseries}
% {\colorbox{myblueii}{\parbox{2cm}{\strut\color{white}\hfill\thesection}}}
% {1em}{#1}
% [{\titleline*[l]{\color{myblueii}\titlerule[1.5pt]}}]
%\titleformat{\subsection}
% {\addtolength{\titlewidth}{2pc}\normalfont\large\sffamily}
% {\colorbox{myblueii}{\parbox{2cm}{\strut\color{white}\hfill\thesubsection}}}
% {1em}{#1}
% [{\titleline*[l]{\color{myblueii}\titlerule[1.5pt]}}]
\usetikzlibrary{calc}
\pagestyle{plain}
\newcounter{chapshift}
\addtocounter{chapshift}{-1}
\newcommand\BoxColor{myblueii}
\def\subsectiontitle{}
\renewcommand{\sectionmark}[1]{\markright{\sffamily\normalsize#1}{}}
\renewcommand{\subsectionmark}[1]{\def\subsectiontitle{#1}}
\usepackage{etoolbox,fancyhdr}
\pagestyle{fancy}
\renewcommand{\headrule}{{\color{myblueii}%
\hrule width\headwidth height\headrulewidth depth\headrulewidth}}
\renewcommand{\chaptermark}[1]{\markboth{\sffamily\normalsize\bfseries \ #1}{}}
\renewcommand{\sectionmark}[1]{\markright{\sffamily\normalsize#1}{}}
\fancyhf{} \fancyhead[LE,RO]{\sffamily\normalsize\colorbox{myblueii}{\color{white}\sffamily\bfseries\strut\quad\thepage\quad}}
\fancyhead[LO]{\textcolor{mybluei} \rightmark%
\begin{tikzpicture}[overlay,remember picture]
\node[fill=\BoxColor,inner sep=-1pt,rectangle,text width=1cm,
text height=28cm,align=center,anchor=north east]
at ($ (current page.north east) $)
{\rotatebox{90}{\parbox{18cm}{%
\centering\textcolor{white}{\bfseries\scshape\thechapter.\leftmark \hspace{2cm}\rightmark\hspace{2cm}\thesubsection~\subsectiontitle}}}};
\end{tikzpicture}}
\fancyhead[RE]{\textcolor{mybluei}\leftmark%
\begin{tikzpicture}[overlay,remember picture]
\node[fill=\BoxColor,inner sep=0pt,rectangle,text width=1cm,
text height=28cm,align=center,anchor=north west]
at ($ (current page.north west) $)
{\rotatebox{90}{\parbox{18cm}{%
\centering\textcolor{white}{\bfseries\scshape\thechapter.\leftmark \hspace{2cm}\rightmark\hspace{2cm}\thesubsection~\subsectiontitle}}}};
\end{tikzpicture}}
\renewcommand{\headrulewidth}{.5pt}
\addtolength{\headheight}{2.5pt}
\newcommand{\footrulecolor}[1]{\patchcmd{\footrule}{\hrule}{\color{#1}\hrule}{}{}}
\renewcommand{\headrulewidth}{.5pt}
\addtolength{\headheight}{2.5pt}
\renewcommand{\footrulewidth}{.5pt}
\fancyfoot[LE,RO]{\footnotesize\bfseries\itshape Foot 1}
\fancyfoot[C]{\footnotesize\bfseries Foot 2}
\fancyfoot[RE,LO]{\footnotesize\bfseries\itshape Foot 3}
\fancypagestyle{plain}{%
\fancyhf{}%
\renewcommand{\headrulewidth}{0pt}
\renewcommand{\footrulewidth}{0pt}
}
\makeatletter
\renewcommand{\cleardoublepage}{
\clearpage\ifodd\c@page\else
\hbox{}
\vspace*{\fill}
\thispagestyle{empty}
\newpage
\fi}
\makeatother
\begin{document}
\chapter{This is how it all began}
\section{Introduction}
\lipsum[4]
\subsection{Sub Introduction}
\lipsum[1-10]
\chapter{This is how it all ended}
\section{Time to say "Goodbye"}
\lipsum
\end{document}
答案1
一种选择：
\documentclass[11pt,fleqn]{book}
\usepackage[english]{babel}
\usepackage{lipsum}
\usepackage{xcolor}
\usepackage{tikz}
\usepackage{mathtools,amsfonts,amssymb,amsthm}
\usepackage[most]{tcolorbox}
\definecolor{ocre}{RGB}{52,177,201}
\definecolor{ultramarine}{RGB}{0,45,97}
\definecolor{mybluei}{RGB}{0,173,239}
\definecolor{myblueii}{RGB}{63,200,244}
\definecolor{myblueiii}{RGB}{199,234,253}
\usepackage{fourier}
\usepackage[explicit,calcwidth]{titlesec}
\renewcommand\thechapter{\arabic{chapter}}
\newcommand\chapnumfont{%
\fontsize{380}{130}\color{myblueii}\selectfont%
}
\newcommand\chapnamefont{%
\normalfont\color{white}\scshape\small\bfseries
}
\titleformat{\chapter}
{\normalfont\huge\filleft}
{}
{0pt}
{\stepcounter{chapshift}%
\begin{tikzpicture}[remember picture,overlay]
\fill[myblueiii]
(current page.north west) rectangle ([yshift=-13cm]current page.north east);
\node[
fill=mybluei,
text width=2\paperwidth,
rounded corners=6cm,
text depth=18cm,
anchor=center,
inner sep=0pt] at (current page.north east) (chaptop)
{\thechapter};%
\node[
anchor=south east,
inner sep=0pt,
outer sep=0pt] (chapnum) at ([xshift=-20pt]chaptop.south)
{\chapnumfont\thechapter};
\node[
anchor=south,
inner sep=0pt] (chapname) at ([yshift=2pt]chapnum.south)
{};
\node[
anchor=north east,
align=right,
inner xsep=0pt] at ([yshift=-0.5cm]chapname.east|-chapnum.south)
{\parbox{.7\textwidth}{\raggedleft#1}};
\end{tikzpicture}%
}
\titleformat{name=\chapter,numberless}
{\normalfont\huge\filleft}
{}
{0pt}
{\begin{tikzpicture}[remember picture,overlay]
\fill[myblueiii]
(current page.north west) rectangle ([yshift=-13cm]current page.north east);
\node[
fill=mybluei,
text width=2\paperwidth,
rounded corners=6cm,
text depth=18cm,
anchor=center,
inner sep=0pt] at (current page.north east) (chaptop)
{};%
\node[
anchor=south east,minimum width=2in,
inner sep=0pt,
outer sep=0pt] (chapnum) at ([xshift=-20pt]chaptop.south)
{};
\node[
anchor=south,
inner sep=0pt] (chapname) at ([yshift=2pt]chapnum.south)
{};
\node[
anchor=north east,
align=right,
inner xsep=0pt] at ([yshift=-0.5cm]chapname.east|-chapnum.south)
{\parbox{.7\textwidth}{\raggedleft#1}};
\end{tikzpicture}%
}
\titlespacing*{\chapter}{0pt}{0pt}{3.5in}
\titlespacing*{name=\chapter,numberless}{0pt}{0pt}{3.5in}
\titleformat{\section}
{\addtolength{\titlewidth}{4pc}\normalfont\Large\sffamily\bfseries}
{\llap{\colorbox{myblueii}{\parbox{2cm}{\strut\color{white}\hfill\thesection}}\hspace{20pt}}}
{0em}{#1}
[{\titleline*[l]{\hspace*{\dimexpr-2cm-20pt-2\fboxsep\relax}\color{myblueii}\titlerule[1.5pt]}}]
\titleformat{\subsection}
{\addtolength{\titlewidth}{2pc}\normalfont\large\sffamily}
{\llap{\colorbox{myblueii}{\parbox{2cm}{\strut\color{white}\hfill\thesubsection}}\hspace{20pt}}}
{0em}{#1}
[{\titleline*[l]{\hspace*{\dimexpr-2cm-20pt-2\fboxsep\relax}\color{myblueii}\titlerule[1.5pt]}}]
\usetikzlibrary{calc}
\pagestyle{plain}
\newcounter{chapshift}
\addtocounter{chapshift}{-1}
\newcommand\BoxColor{myblueii}
\def\subsectiontitle{}
\renewcommand{\sectionmark}[1]{\markright{\sffamily\normalsize#1}{}}
\renewcommand{\subsectionmark}[1]{\def\subsectiontitle{#1}}
\usepackage{etoolbox,fancyhdr}
\pagestyle{fancy}
\renewcommand{\headrule}{{\color{myblueii}%
\hrule width\headwidth height\headrulewidth depth\headrulewidth}}
\renewcommand{\chaptermark}[1]{\markboth{\sffamily\normalsize\bfseries \ #1}{}}
\renewcommand{\sectionmark}[1]{\markright{\sffamily\normalsize#1}{}}
\fancyhf{} \fancyhead[LE,RO]{\sffamily\normalsize\colorbox{myblueii}{\color{white}\sffamily\bfseries\strut\quad\thepage\quad}}
\fancyhead[LO]{\textcolor{mybluei} \rightmark%
\begin{tikzpicture}[overlay,remember picture]
\node[fill=\BoxColor,inner sep=-1pt,rectangle,text width=1cm,
text height=28cm,align=center,anchor=north east]
at ($ (current page.north east) $)
{\rotatebox{90}{\parbox{18cm}{%
\centering\textcolor{white}{\bfseries\scshape\thechapter.\leftmark \hspace{2cm}\rightmark\hspace{2cm}\thesubsection~\subsectiontitle}}}};
\end{tikzpicture}}
\fancyhead[RE]{\textcolor{mybluei}\leftmark%
\begin{tikzpicture}[overlay,remember picture]
\node[fill=\BoxColor,inner sep=0pt,rectangle,text width=1cm,
text height=28cm,align=center,anchor=north west]
at ($ (current page.north west) $)
{\rotatebox{90}{\parbox{18cm}{%
\centering\textcolor{white}{\bfseries\scshape\thechapter.\leftmark \hspace{2cm}\rightmark\hspace{2cm}\thesubsection~\subsectiontitle}}}};
\end{tikzpicture}}
\renewcommand{\headrulewidth}{.5pt}
\addtolength{\headheight}{2.5pt}
\newcommand{\footrulecolor}[1]{\patchcmd{\footrule}{\hrule}{\color{#1}\hrule}{}{}}
\renewcommand{\headrulewidth}{.5pt}
\addtolength{\headheight}{2.5pt}
\renewcommand{\footrulewidth}{.5pt}
\fancyfoot[LE,RO]{\footnotesize\bfseries\itshape Foot 1}
\fancyfoot[C]{\footnotesize\bfseries Foot 2}
\fancyfoot[RE,LO]{\footnotesize\bfseries\itshape Foot 3}
\fancypagestyle{plain}{%
\fancyhf{}%
\renewcommand{\headrulewidth}{0pt}
\renewcommand{\footrulewidth}{0pt}
}
\makeatletter
\renewcommand{\cleardoublepage}{
\clearpage\ifodd\c@page\else
\hbox{}
\vspace*{\fill}
\thispagestyle{empty}
\newpage
\fi}
\makeatother
\begin{document}
\chapter{This is how it all began}
\section{Introduction}
\lipsum[4]
\subsection{Sub Introduction}
\lipsum[1-10]
\chapter{This is how it all ended}
\section{Time to say "Goodbye"}
\lipsum
\end{document}
