proper type-setting of cartouches (requires T1);
\usepackage[T1]{fontenc} is default for mkroot;
\usepackage[utf8]{inputenc} is obsolete in lualatex;
\documentclass[11pt,a4paper]{article}
\usepackage[T1]{fontenc}
\usepackage{isabelle,isabellesym}
\usepackage{pdfsetup}
\urlstyle{rm}
\isabellestyle{it}
\begin{document}
\title{Isabelle/CTT --- Constructive Type Theory \\
with extensional equality and without universes}
\author{Larry Paulson}
\maketitle
\tableofcontents
\parindent 0pt\parskip 0.5ex
\input{session}
\end{document}