\errorcontextlines=99
\documentclass[a4paper,english]{birthday}
\usepackage[utf8]{inputenc}
\usepackage{amsmath,babel}
\usepackage{lipsum}
\title{Stable bifurcations of the Schrödinger cat equation}
\author{A.N. Onymous\thanks{Supported by NFS grant 0000-999-000.}
   and Cat L. Over\thanks{Meow!}}
\contact[a.n.onymous@example.edu]
 {A.N. Onymous, Dept of Math, University of Somewhere,
   P.O. Box 616, Somewhere City, Somecountry}
\contact[sooa@example.edu]
 {Cat L. Over, Kittenville College, Undogistan}
\begin{document}
\begin{abstract}
  \lipsum[1]
\end{abstract}
\begin{classification}
Primary XX-YY; Secondary ZZ-UU, VV-WW.
\end{classification}

\begin{keywords}
Burble modules, $L^{-\infty}$-functions, Some conjecture.
\end{keywords}

\section{Introducing the problem}
\[\Biggl(\biggl(\Bigl(\bigl((\cdot)\bigr)\Bigr)\biggr)\Biggr)\]
\lipsum[2-5]
\section{Solving the problem}
\lipsum[6-7]
\subsection{Some more details}
\lipsum[8-10]
\subsubsection{Nitty-gritty details}
\lipsum[11-12]
\end{document}