main_preamble.sty

\documentclass[12pt, a4paper, oneside]{book}

\usepackage{catchfilebetweentags}
\ExecuteMetaData[../../preamble.sty]{preamble}

\addto\captionsrussian{\renewcommand{\chaptername}{Лекция}}

\let\MakeUppercase\relax

\lfoot{}
\cfoot{}
\rfoot{}
\lhead{\leftmark}

\usepackage{tocloft}
\advance\cftsecnumwidth -1em\relax
\advance\cftsubsecindent -1em\relax
\advance\cftsubsecnumwidth -1em\relax
\advance\cftsubsubsecindent -3em\relax
\advance\cftsubsubsecnumwidth -1em\relax

\setcounter{tocdepth}{3}
\setcounter{secnumdepth}{3}

\usepackage{titletoc}
\titlecontents*{chapter}% <section-type>
[0pt]% <left>
{}% <above-code>
{\bfseries\chaptername\ \thecontentslabel\quad}% <numbered-entry-format>
{}% <numberless-entry-format>
{\bfseries\hfill\contentspage}% <filler-page-format>

\let\endtitlepage\relax

\patchcmd{\chapter}{\thispagestyle{plain}}{\thispagestyle{fancy}}{}{}

\usepackage{remreset}
\makeatletter
\@removefromreset{section}{chapter}
\makeatother

\usepackage{chngcntr}
\counterwithout{equation}{chapter}

\renewcommand{\thesection}{\arabic{section}}
\author{Михайлов Максим}