preamble.tex

\usepackage{booktabs}
\usepackage{geometry}%[showframes]
%\geometry{paperwidth=170mm, paperheight=240mm, left=42pt, top=40pt, textwidth=280pt, marginparsep=20pt, marginparwidth=100pt, textheight=560pt, footskip=40pt}
%\geometry{letterpaper,margin=2.25cm}
\usepackage{amsthm}
\usepackage{amsmath,amssymb,amsfonts}
\usepackage{fontspec, xltxtra, xunicode} % Habilita el uso de cualquier fuente
\usepackage{microtype} % Mejora la presentacion de las fuentes
\usepackage[colorlinks=true, pdfborder={0 0 0}]{hyperref}
\usepackage{tcolorbox}  % Para los text-box con colores
\usepackage{graphicx}
\usepackage{tikz}
\usepackage{chemfig}
\usepackage[framemethod=default]{mdframed} % Required for creating the theorem, definition, exercise and corollary boxes
\makeatletter
\def\thm@space@setup{%
  \thm@preskip=8pt plus 2pt minus 4pt
  \thm@postskip=\thm@preskip
}
\makeatother
\definecolor{ocre}{RGB}{52,177,201}
\newenvironment{blackbox}{\par\vspace{10pt}% Vertical white space above the remark and normal font size
    \begin{list}{}{
            \leftmargin=35pt % Indentation on the left
            \rightmargin=25pt}\item\ignorespaces % Indentation on the right
              \makebox[-2.5pt]{\begin{tikzpicture}[overlay]
                      \node[draw=ocre!60,line width=1pt,circle,fill=ocre!25,font=\sffamily\bfseries,inner sep=2pt,outer sep=0pt] at (-15pt,0pt){\textcolor{ocre}{R}};\end{tikzpicture}} % Orange R in a circle
              \advance\baselineskip -1pt}{\end{list}\vskip5pt} % Tighter line spacing and white space after remark
              
\newenvironment{infobox}{\par\vspace{10pt}% Vertical white space above the remark and normal font size
    \begin{list}{}{
            \leftmargin=35pt % Indentation on the left
            \rightmargin=25pt}\item\ignorespaces % Indentation on the right
              \makebox[-2.5pt]{\begin{tikzpicture}[overlay]
                      \node[draw=ocre!60,line width=1pt,circle,fill=ocre!25,font=\sffamily\bfseries,inner sep=2pt,outer sep=0pt] at (-15pt,0pt){\textcolor{ocre}{R}};\end{tikzpicture}} % Orange R in a circle
              \advance\baselineskip -1pt}{\end{list}\vskip5pt} % Tighter line spacing and white space after remark