LuaLateX: Problem with microtype \textls and center environment

Question

I want to use \textls to reduce letterspacing for citing works/compositions. If I use it in the titlepage inside a center environment it gets a bit messy. As in other examples, it seems like the lines somehow are moved to the right. The command inside normal text seems to work fine.

I use LuaLateX to compile.

MWE:

\documentclass{article}

\usepackage{microtype}
\usepackage{geometry}
\geometry{a4paper, top=25mm, left=20mm, right=20mm, bottom=30mm,
headsep=0mm, footskip=12mm}

\usepackage{fontspec}
\setmainfont[SmallCapsFont={Latin Modern Roman Caps}]{Latin Modern Roman}

\newcommand{\work}[1]{\textsc{\textls[-50]{#1}}}

\begin{document}

    \begin{center}
    \huge
        Immanuel Kants \work{Kritik der praktischen Vernunft},

        \work{Kritik der reinen Vernunft} und

        \work{Kritik der Urteilskraft}

    \end{center}

\end{document}

Answer 1

You can use the LetterSpace feature instead:

\documentclass{article}

\usepackage{microtype}
\usepackage{geometry}
\geometry{a4paper, top=25mm, left=20mm, right=20mm, bottom=30mm,
headsep=0mm, footskip=12mm}

\usepackage{fontspec}
\setmainfont[SmallCapsFont={Latin Modern Roman Caps},
             SmallCapsFeatures={LetterSpace=-6}]{Latin Modern Roman}

\newcommand{\work}[1]{\textsc{{#1}}}

\begin{document}

    \begin{center}
    \huge
        Immanuel Kant's \work{Kritik der praktischen Vernunft},

         \work{Kritik der reinen Vernunft} und

        \work{Kritik der Urteilskraft}

    \end{center}

\end{document}

You can also burry the text in a fbox with invisible rules:

\newcommand{\work}[1]{{\fboxsep=0pt\fboxrule=0pt\fbox{\textsc{\textls[-50]{#1}}}}}

It also works if you add word joiners

 \newcommand{\work}[1]{\textsc{^^^^2060\textls[-50]{#1}^^^^2060}}

but only if the text is on one line. If there is a line break centering will be lost again.

Answer 2

as a workaround use

    ~\work{Kritik der reinen Vernunft} und~