% Margins
\usepackage[inner=35mm, outer=20mm, top=30mm, bottom=25mm]{geometry}

% Set line spacing to 1.15
\usepackage{setspace}
\linespread{1.15}

% Typography
\usepackage{iftex}
\ifluatex
    \usepackage{libertinus-otf}
\else
    \usepackage{mathtools} % Math improvements
    \usepackage{libertinus} % Libertinus font for text and math
    \usepackage[T1]{fontenc} % Use T1 font encoding
    \usepackage{textcomp} % Additional symbols
    \usepackage[varqu, varl]{inconsolata} % Better monospace font (with alternative "quote" [varqu] and "l" [varl])
    %\usepackage{libertinust1math} % Libertinus math font
\fi

\usepackage[english]{babel} % Typographical rules
\usepackage{microtype} % Micro-typography improvements (slightly more compact, better to read)

% Use sans-serif font for sections
\usepackage{titlesec}
\titleformat{\chapter}[display]{\normalfont\Large\sffamily\bfseries}{\chaptertitlename\ \thechapter}{20pt}{\Huge}
\titleformat{\section}{\normalfont\large\sffamily\bfseries}{\thesection}{1em}{}
\titleformat{\subsection}{\normalfont\normalsize\sffamily\bfseries}{\thesubsection}{1em}{}
\titleformat{\subsubsection}[runin]{\normalfont\normalsize\sffamily\mdseries}{\thesubsubsection}{1em}{}
\titleformat{\paragraph}[runin]{\normalfont\normalsize\sffamily\bfseries}{\theparagraph}{1em}{}

% Headers
\usepackage{emptypage} % Remove headers and footers on empty pages
\usepackage{etoolbox} % Patching commands
\usepackage{fancyhdr} % Headers and footers

\pagestyle{fancy} % Use fancy headers and footers
\fancyhf{} % Clear headers and footers
\fancyhead[LO, RE]{\small\leftmark} % Chapter in the left on odd pages and right on even pages
\fancyfoot[C]{\thepage} % Page number in the center

\appto\mainmatter{
    \renewcommand{\sectionmark}[1]{\markright{\thesection.\ #1}}
    \renewcommand{\chaptermark}[1]{\markboth{\chaptername~\thechapter~--\ #1}{}}
    \fancyhead[RE]{\small\rightmark}
    \fancyhead[LO]{\small\leftmark}
}

\setlength{\headheight}{14pt}