% \iffalse meta-comment -------------------------------------------------------
% Copyright 2015 Matthias Vogelgesang and the LaTeX community. A full list of
% contributors can be found at
%
%     https://github.com/matze/mtheme/graphs/contributors
%
% and the original template was based on the HSRM theme by Benjamin Weiss.
%
% This work is licensed under a Creative Commons Attribution-ShareAlike 4.0
% International License (https://creativecommons.org/licenses/by-sa/4.0/).
%% ---------------------------------------------------------------------------
%% Copyright 2024 Johan Larsson and contributors
% ------------------------------------------------------------------------- \fi
% \iffalse
%<*package>
\NeedsTeXFormat{LaTeX2e}
\ProvidesExplPackage{moloch-talk}{2026-10-15}{2.3.0}{Moloch theme for ltx-talk}
%</package>
% \fi
% \CheckSum{0}
% \StopEventually{}
% \iffalse
%<*package>
% ------------------------------------------------------------------------- \fi
%
% \subsection{Moloch for \texttt{ltx-talk}}
%
% This package brings the Moloch design to \texttt{ltx-talk}, the experimental
% presentation class by Joseph Wright. Unlike Beamer, \texttt{ltx-talk} has no
% theme mechanism: its author states explicitly that themes are not part of the
% \texttt{ltx-talk} approach, and that appearance is instead adjusted through
% the \LaTeX3 template layer. This package is therefore an ordinary package
% that a document loads after the class:
%
% \begin{verbatim}
% \DocumentMetadata{lang=en-US,tagging=on}
% \documentclass{ltx-talk}
% \usepackage{moloch-talk}
% \end{verbatim}
%
% Both the class and this package are experimental. \texttt{ltx-talk} is a
% 0.x release whose author warns that ``changes may occur to almost all
% interfaces'', so this package may need to follow those changes.
%
% \subsection{Class Guard}
%
% There is no sensible way to recover if the class is missing, and the errors
% that would follow (undefined templates and instances) are unhelpful, so fail
% early with a clear message.
%
%    \begin{macrocode}
\msg_new:nnnn { moloch-talk } { wrong-class }
  { The~'moloch-talk'~package~requires~the~'ltx-talk'~class. }
  {
    Load~the~class~first:~\iow_char:N\\documentclass{ltx-talk}.~
    For~Beamer~presentations~use~\iow_char:N\\usetheme{moloch}~instead.
  }
\cs_if_exist:NF \ps@talk
  { \msg_fatal:nn { moloch-talk } { wrong-class } }
%    \end{macrocode}
%
% \subsection{Colors}
%
% The color names are the same as in the Beamer theme, so that recipes carry
% over between the two and the two ports stay conceptually in sync. Only the
% default color theme is provided; the alternative themes of the Beamer version
% (\texttt{tomorrow}, \texttt{catppuccin}, and so on) are not ported yet.
%
% \begin{macro}{\__moloch_colors_light:}
%    The light variant, transcribed from the Beamer color theme.
%    \begin{macrocode}
\cs_new_protected:Npn \__moloch_colors_light:
  {
    \definecolor { mNormaltextFg } { HTML } { 23373B }
    \colorlet    { mNormaltextBg } { black!2 }
    \definecolor { mAlertFg }      { HTML } { EB811B }
    \definecolor { mExampleFg }    { RGB }  { 0 , 128 , 128 }
    \colorlet    { mFrametitleFg } { mNormaltextBg }
    \colorlet    { mFrametitleBg } { mNormaltextFg }
    \colorlet    { mProgressbarFg } { mAlertFg }
    \colorlet    { mProgressbarBg } { mProgressbarFg!50!black!30 }
    \colorlet    { mTitleseparatorFg } { mProgressbarFg }
    \colorlet    { mStandoutFg }   { mNormaltextBg }
    \colorlet    { mStandoutBg }   { mNormaltextFg }
    \colorlet    { mFootnoteFg }   { mNormaltextFg!90 }
  }
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\__moloch_colors_dark:}
%    The dark variant. Note that it is not simply the light variant inverted:
%    the alert and example colors are lightened for contrast against the dark
%    background, exactly as in the Beamer theme.
%    \begin{macrocode}
\cs_new_protected:Npn \__moloch_colors_dark:
  {
    \colorlet    { mNormaltextFg } { black!2 }
    \definecolor { mNormaltextBg } { HTML } { 23373B }
    \definecolor { mAlertFg }      { HTML } { EF9F76 }
    \definecolor { mExampleFg }    { HTML } { 5ABFB5 }
    \colorlet    { mFrametitleFg } { mNormaltextBg }
    \colorlet    { mFrametitleBg } { black!15 }
    \colorlet    { mProgressbarFg } { mAlertFg }
    \colorlet    { mProgressbarBg } { mProgressbarFg!50!black!30 }
    \colorlet    { mTitleseparatorFg } { mProgressbarFg }
    \colorlet    { mStandoutFg }   { mNormaltextBg }
    \colorlet    { mStandoutBg }   { black!15 }
    \colorlet    { mFootnoteFg }   { mNormaltextFg!90 }
  }
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\__moloch_colors_apply:}
%    The class uses three semantic colors. Mapping \texttt{structure} to the
%    normal text color reproduces Moloch's convention that block titles, list
%    labels and table-of-contents entries are simply the body color in bold,
%    rather than a separate accent color.
%
%    Selecting the body color again also updates the current color after a
%    variant change. Redefining its name alone leaves the previously selected
%    color active, which would make dark text disappear on a dark background.
%    Inside a standout, both the current color and the structure color must
%    instead follow the standout foreground to retain contrast.
%    \begin{macrocode}
\bool_new:N \l__moloch_standout_bool
\cs_new_protected:Npn \__moloch_colors_apply:
  {
    \bool_if:NTF \l__moloch_standout_bool
      {
        \DeclareColor { structure } { mStandoutFg }
        \color_select:n { mStandoutFg }
      }
      {
        \DeclareColor { structure } { mNormaltextFg }
        \color_select:n { mNormaltextFg }
      }
    \DeclareColor { alert }     { mAlertFg }
    \DeclareColor { example }   { mExampleFg }
  }
%    \end{macrocode}
% \end{macro}
%
% \subsection{Options}
%
% The option surface is deliberately much smaller than the Beamer theme's.
% Anything not covered here is adjusted with the class's own interfaces,
% \cs{EditInstance} and \cs{DeclareColor}.
%
%    \begin{macrocode}
\tl_new:N   \l__moloch_progressbar_tl
\tl_new:N   \l__moloch_sectionpage_tl
\dim_new:N  \l__moloch_progressbar_dim
\dim_new:N  \l__moloch_titlerule_dim
\bool_new:N \l__moloch_framenumber_bool

\keys_define:nn { moloch }
  {
    variant .choice: ,
    variant / light .code:n =
      { \__moloch_colors_light: \__moloch_colors_apply: } ,
    variant / dark .code:n =
      { \__moloch_colors_dark: \__moloch_colors_apply: } ,
    progressbar .choices:nn =
      { none , head , frametitle , foot }
      { \tl_set_eq:NN \l__moloch_progressbar_tl \l_keys_choice_tl } ,
    progressbar-linewidth .dim_set:N = \l__moloch_progressbar_dim ,
    sectionpage .choices:nn =
      { none , simple , progressbar }
      { \tl_set_eq:NN \l__moloch_sectionpage_tl \l_keys_choice_tl } ,
    titleseparator-linewidth .dim_set:N = \l__moloch_titlerule_dim ,
    framenumber .bool_set:N = \l__moloch_framenumber_bool
  }
%    \end{macrocode}
%
%    The defaults match the Beamer theme: no progress bar, section pages with
%    a progress bar, a 1pt bar and a 0.5pt title separator.
%
%    \begin{macrocode}
\keys_set:nn { moloch }
  {
    variant = light ,
    progressbar = none ,
    progressbar-linewidth = 1pt ,
    sectionpage = progressbar ,
    titleseparator-linewidth = 0.5pt ,
    framenumber = true
  }
\ProcessKeyOptions [ moloch ]
%    \end{macrocode}
%
% \begin{macro}{\molochset}
%    Options can also be set after loading. Changing variants selects the new
%    body color. Inside a frame, the palette and page options are saved globally
%    because the class closes the body's typesetting groups before drawing the
%    header, footer, and background. The frame and slide numbers limit those
%    saved settings to the pages produced by the current body.
%
%    Nested groups must still restore their enclosing settings. The class
%    runs its tagging setup in the box surrounding the body, immediately
%    before opening the body's box and color groups. Recording the depth of
%    the inner group lets us refresh the saved settings as nested groups
%    close, while keeping the final body settings available after the body
%    itself closes.
%    \begin{macrocode}
\int_new:N \l__moloch_body_group_int
\cs_new_eq:NN \__moloch_slide_tag_on_begin: \__talk_slide_tag_on_begin:
\cs_set_protected:Npn \__talk_slide_tag_on_begin:
  {
    \__moloch_slide_tag_on_begin:
    \int_set:Nn \l__moloch_body_group_int
      { \tex_currentgrouplevel:D + 2 }
  }
\cs_new_eq:NN \__moloch_slide_tag_off_begin: \__talk_slide_tag_off_begin:
\cs_set_protected:Npn \__talk_slide_tag_off_begin:
  {
    \__moloch_slide_tag_off_begin:
    \int_set:Nn \l__moloch_body_group_int
      { \tex_currentgrouplevel:D + 2 }
  }
\int_new:N \g__moloch_settings_frame_int
\int_new:N \g__moloch_settings_slide_int
\int_gset:Nn \g__moloch_settings_frame_int { -1 }
\tl_new:N \g__moloch_frame_settings_tl
\tl_new:N \l__moloch_color_spec_tl
\cs_new_protected:Npn \__moloch_frame_settings_save:
  {
    \int_gset:Nn \g__moloch_settings_frame_int { \value { frame } }
    \int_gset:Nn \g__moloch_settings_slide_int { \value { slide } }
    \tl_gset:Ne \g__moloch_frame_settings_tl
      {
        \exp_not:N \keys_set:nn { moloch }
          {
            progressbar = \exp_not:V \l__moloch_progressbar_tl ,
            progressbar-linewidth = \dim_use:N \l__moloch_progressbar_dim ,
            framenumber = \bool_if:NTF \l__moloch_framenumber_bool
              { true } { false }
          }
      }
    \clist_map_inline:nn
      {
        mNormaltextFg , mNormaltextBg , mAlertFg , mExampleFg ,
        mFrametitleFg , mFrametitleBg , mProgressbarFg , mProgressbarBg ,
        mTitleseparatorFg , mStandoutFg , mStandoutBg , mFootnoteFg ,
        structure , alert , example
      }
      {
        \extractcolorspec {##1} \l__moloch_color_spec_tl
        \tl_gput_right:Ne \g__moloch_frame_settings_tl
          { \exp_not:N \definecolor {##1} \exp_not:V \l__moloch_color_spec_tl }
      }
    \int_compare:nNnT
      { \tex_currentgrouplevel:D } > \l__moloch_body_group_int
      { \group_insert_after:N \__moloch_frame_settings_save: }
  }
\NewDocumentCommand \molochset { m }
  {
    \keys_set:nn { moloch } {#1}
    \bool_if:NT \l__talk_frame_bool { \__moloch_frame_settings_save: }
  }
%    \end{macrocode}
% \end{macro}
%
% \subsection{Frame Title Band}
%
% Moloch's frame title sits in a band that spans the full paper width, with the
% title one strut height above the band's lower edge and two above its baseline
% --- three strut heights in total, measured in the frame title font.
%
% The class already draws a full-width band for the running header, sized from
% the \texttt{geometry} package's top margin and header separation. So rather
% than rebuilding the header template, the proportions are obtained by setting
% those two lengths: \texttt{geometry}'s \texttt{tmargin} measures from the top
% of the paper to the top of the body text, which is exactly the band's visible
% height.
%
%    \begin{macrocode}
\dim_new:N \g__moloch_band_dim
\dim_new:N \g__moloch_headsep_dim
\group_begin:
  \large
  \dim_gset:Nn \g__moloch_band_dim { 3 \ht \strutbox }
  \dim_gset:Nn \g__moloch_headsep_dim { \ht \strutbox }
\group_end:
%    \end{macrocode}
%
%    The frame title also hangs closer to the edge of the paper than the body
%    text does. This is one of the places where the class's default differs
%    from Moloch: it aligns the frame title with the body text instead. The
%    measure is taken in the body font, as in the Beamer theme.
%
%    \begin{macrocode}
\dim_new:N \g__moloch_hmargin_dim
\group_begin:
  \normalsize
  \dim_gset:Nn \g__moloch_hmargin_dim { 0.85 \ht \strutbox }
\group_end:
%    \end{macrocode}
%
%    The footer sits lower than the class puts it, so that the frame number
%    ends up on the same line as in the Beamer theme, whose footer leaves 4pt
%    below the number. The distance from the bottom of the body text to the
%    footer baseline is what \texttt{geometry} calls the foot skip.
%
%    \begin{macrocode}
\dim_const:Nn \c__moloch_footer_baseline_dim { 4pt }
\dim_new:N \g__moloch_footskip_dim
\dim_gset:Nn \g__moloch_footskip_dim
  { \Gm@bmargin - \c__moloch_footer_baseline_dim }
%    \end{macrocode}
%
%    The header box also has to be tall enough to hold the band, or every
%    frame reports an overfull box while the output routine is active.
%
%    \begin{macrocode}
\use:e
  {
    \exp_not:N \geometry
      {
        tmargin = \dim_use:N \g__moloch_band_dim ,
        headheight = \dim_use:N \g__moloch_band_dim ,
        headsep = \dim_use:N \g__moloch_headsep_dim ,
        footskip = \dim_use:N \g__moloch_footskip_dim
      }
  }
%    \end{macrocode}
%
%    With the geometry in place only the colors and the font need changing.
%    The header's \texttt{height} key is left at its default, which is written
%    in terms of the \texttt{geometry} lengths and so follows the change above.
%
%    \begin{macrocode}
\EditInstance { header } { std }
  {
    background-color = mFrametitleBg ,
    color = mFrametitleFg ,
    left-hspace = \g__moloch_hmargin_dim
  }
\EditInstance { frametitle } { header }
  { font = \large \bfseries }
%    \end{macrocode}
%
% \subsection{Rules and the Progress Bar}
%
% \begin{macro}{\__moloch_rule:nnn}
%    A rule given as width, height and depth. The class has an equivalent
%    helper, but it is internal to the class, so this package provides its own.
%    \begin{macrocode}
\dim_new:N \l__moloch_rule_wd_dim
\dim_new:N \l__moloch_rule_ht_dim
\dim_new:N \l__moloch_rule_dp_dim
\cs_new_protected:Npn \__moloch_rule:nnn #1#2#3
  {
    \group_begin:
      \dim_set:Nn \l__moloch_rule_wd_dim { #1 }
      \dim_set:Nn \l__moloch_rule_dp_dim { 0pt - ( #3 ) }
      \dim_set:Nn \l__moloch_rule_ht_dim { ( #2 ) + ( #3 ) }
      \rule
        [ \l__moloch_rule_dp_dim ]
        { \l__moloch_rule_wd_dim }
        { \l__moloch_rule_ht_dim }
    \group_end:
  }
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\__moloch_progress_frac:}
%    How far through the presentation we are, as a number between 0 and 1. The
%    fallback of 100 total frames keeps the first compilation, when the total
%    is not yet known, from producing an over-long bar; the Beamer theme uses
%    the same guard.
%    \begin{macrocode}
\cs_new:Npn \__moloch_progress_frac:
  {
    \fp_eval:n
      {
        min
          (
            1 ,
            \int_use:N \c@frame /
            max ( 1 , \property_ref:nnn { lastpage } { totalframes } { 100 } )
          )
      }
  }
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\__moloch_progress_width:n}
%    The filled portion of a bar of the given width. The fraction cannot simply
%    be placed in front of the width, because that is only valid when the width
%    is a length register rather than an expression.
%    \begin{macrocode}
\cs_new:Npn \__moloch_progress_width:n #1
  {
    \fp_to_dim:n
      { \__moloch_progress_frac: * \dim_to_fp:n { #1 } }
  }
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\__moloch_progressbar:nn}
%    The bar itself, given a height and a depth relative to the current
%    baseline. It is drawn as an overlapping box of zero width, so that it can
%    be placed at the start of the header or footer without disturbing what
%    follows.
%
%    Drawing the bar here, rather than in a \texttt{shipout/background} hook,
%    is what makes it obey the page style: a background hook cannot tell a
%    plain page from an ordinary one, and the bar would then also appear on the
%    title page, on section pages and on standout frames.
%    \begin{macrocode}
\cs_new_protected:Npn \__moloch_progressbar:nn #1#2
  {
    \hbox_overlap_right:n
      {
        \skip_horizontal:n { -\Gm@lmargin }
        \group_begin:
          \color_select:n { mProgressbarBg }
          \__moloch_rule:nnn { \paperwidth } {#1} {#2}
        \group_end:
        \skip_horizontal:n { -\paperwidth }
        \group_begin:
          \color_select:n { mProgressbarFg }
          \__moloch_rule:nnn
            { \__moloch_progress_width:n { \paperwidth } } {#1} {#2}
        \group_end:
      }
  }
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\__moloch_progressbar_head:}
% \begin{macro}{\__moloch_progressbar_frametitle:}
% \begin{macro}{\__moloch_progressbar_foot:}
%    The three positions. The header baseline sits one header separation above
%    the lower edge of the band, so a negative height places the bar exactly at
%    that edge for the \texttt{frametitle} position. The top of the page is
%    therefore one header separation closer to the baseline than the top margin.
%    \begin{macrocode}
\cs_new_protected:Npn \__moloch_progressbar_head:
  {
    \__moloch_progressbar:nn
      { \Gm@tmargin - \headsep }
      { \l__moloch_progressbar_dim - \Gm@tmargin + \headsep }
  }
\cs_new_protected:Npn \__moloch_progressbar_frametitle:
  {
    \__moloch_progressbar:nn
      { -\headsep }
      { \headsep + \l__moloch_progressbar_dim }
  }
\cs_new_protected:Npn \__moloch_progressbar_foot:
  {
    \__moloch_progressbar:nn
      { \l__moloch_progressbar_dim - \Gm@bmargin + \footskip }
      { \Gm@bmargin - \footskip }
  }
%    \end{macrocode}
% \end{macro}
% \end{macro}
% \end{macro}
%
% \begin{macro}{\__moloch_progress_rule:n}
%    A horizontal progress bar of a given width, for use on section pages,
%    where it is part of the text rather than part of the page furniture. It
%    hangs below the baseline rather than sitting on it, as the Beamer theme's
%    does.
%    \begin{macrocode}
\cs_new_protected:Npn \__moloch_progress_rule:n #1
  {
    \leavevmode
    \hbox_overlap_right:n
      {
        \group_begin:
          \color_select:n { mProgressbarBg }
          \__moloch_rule:nnn {#1} { 0pt } { \l__moloch_progressbar_dim }
        \group_end:
      }
    \hbox_overlap_right:n
      {
        \group_begin:
          \color_select:n { mProgressbarFg }
          \__moloch_rule:nnn
            { \__moloch_progress_width:n {#1} }
            { 0pt }
            { \l__moloch_progressbar_dim }
        \group_end:
      }
    \rule {#1} { 0pt }
  }
%    \end{macrocode}
% \end{macro}
%
% \subsection{Page Style}
%
% A separate footer instance keeps the class's own footer available through
% \cs{pagestyle}\{talk\}. It uses the class's footer elements and short
% metadata, but places a final frame number at the right edge without the
% trailing glue that the class's footer template adds.
%
% Both edges sit closer to the paper edge than the body text does, as in the
% Beamer theme. The skips outside the box keep its total width equal to the
% text width, so the output routine can place it normally.
%
%    \begin{macrocode}
\tl_new:N \l__moloch_footer_color_tl
\tl_new:N \l__moloch_footer_font_tl
\tl_new:N \l__moloch_footer_separator_tl
\tl_new:N \l__moloch_footer_metadata_tl
\clist_new:N \l__moloch_footer_order_clist
\seq_new:N \l__moloch_footer_elements_seq
\dim_new:N \l__moloch_footer_left_dim
\dim_new:N \l__moloch_footer_right_dim
\DeclareTemplateInterface { footer } { moloch } { 0 }
  {
    color         : tokenlist = mFootnoteFg ,
    font          : tokenlist = \tiny ,
    element-order : commalist = { framenumber } ,
    left-hspace   : length = 4pt ,
    right-hspace  : length = 5pt ,
    separator     : tokenlist = \hfil
  }
\cs_new:Npn \__moloch_footer_metadata:n #1
  {
    \cs_if_exist:cTF { @ short #1 }
      { @ short #1 }
      { @ #1 }
  }
\cs_new_protected:Npn \__moloch_footer_element:n #1
  {
    \tl_set:Ne \l__moloch_footer_metadata_tl
      { \__moloch_footer_metadata:n {#1} }
    \ExpandArgs { nnv } \UseInstance { footer-element } {#1}
      { \l__moloch_footer_metadata_tl }
  }
\DeclareTemplateCode { footer } { moloch } { 0 }
  {
    color         = \l__moloch_footer_color_tl ,
    font          = \l__moloch_footer_font_tl ,
    element-order = \l__moloch_footer_order_clist ,
    left-hspace   = \l__moloch_footer_left_dim ,
    right-hspace  = \l__moloch_footer_right_dim ,
    separator     = \l__moloch_footer_separator_tl
  }
  {
    \seq_clear:N \l__moloch_footer_elements_seq
    \clist_map_inline:Nn \l__moloch_footer_order_clist
      {
        \bool_lazy_or:nnT
          { ! \str_if_eq_p:nn {##1} { framenumber } }
          { \l__moloch_framenumber_bool }
          {
            \tl_if_empty:cF { \__moloch_footer_metadata:n {##1} }
              { \seq_put_right:Nn \l__moloch_footer_elements_seq {##1} }
          }
      }
    \skip_horizontal:n { \l__moloch_footer_left_dim - \Gm@lmargin }
    \hbox_to_wd:nn
      { \paperwidth - \l__moloch_footer_left_dim - \l__moloch_footer_right_dim }
      {
        \tl_if_empty:NF \l__moloch_footer_color_tl
          { \color_select:V \l__moloch_footer_color_tl }
        \l__moloch_footer_font_tl
        \seq_map_indexed_inline:Nn \l__moloch_footer_elements_seq
          {
            \int_compare:nNnTF {##1} > { 1 }
              { \l__moloch_footer_separator_tl }
              { \str_if_eq:nnT {##2} { framenumber } { \hfil } }
            \__moloch_footer_element:n {##2}
          }
        \str_if_eq:eeF
          { \seq_item:Nn \l__moloch_footer_elements_seq { -1 } }
          { framenumber }
          { \hfil }
      }
    \skip_horizontal:n { \l__moloch_footer_right_dim - \Gm@rmargin }
  }
\DeclareInstance { footer } { moloch } { moloch } { }
%    \end{macrocode}
%
% The header is drawn in an overlapping box so that the progress bar can
% follow it at the same horizontal position. This keeps the header's
% background from covering a bar placed at the top of the page.
%
%    \begin{macrocode}
\cs_new_nopar:Npn \ps@moloch
  {
    \cs_set_nopar:Npn \@oddhead
      {
        \hbox_overlap_right:n { \UseInstance { header } { std } }
        \str_case:Vn \l__moloch_progressbar_tl
          {
            { head }       { \__moloch_progressbar_head: }
            { frametitle } { \__moloch_progressbar_frametitle: }
          }
        \hfil
      }
    \cs_set_nopar:Npn \@oddfoot
      {
        \str_if_eq:VnT \l__moloch_progressbar_tl { foot }
          { \__moloch_progressbar_foot: }
        \UseInstance { footer } { moloch }
      }
    \cs_set_eq:NN \@evenhead \@oddhead
    \cs_set_eq:NN \@evenfoot \@oddfoot
  }
\pagestyle { moloch }
%    \end{macrocode}
%
% \subsection{Lists}
%
% Draw the same circle, square, and triangle as the Beamer theme so that the
% markers do not depend on font glyphs. The class's list instances use the
% standard label commands, which keeps explicit item labels and the class's
% tagging and overlay handling intact. The fourth level retains its class
% default, since Beamer only supports three levels.
%
% The circle and triangle overhang slightly to align their visible edges
% with the square, just as they do in the Beamer theme.
%
% The class selects colors through the LaTeX3 color layer, while PGF reads
% xcolor's current color. Export the current label color explicitly so the
% drawn markers also follow dark variants and custom label colors.
%
%    \begin{macrocode}
\ExplSyntaxOff
\RequirePackage{pgf}
\ExplSyntaxOn

\tl_new:N \l__moloch_itemize_color_tl
\cs_new_protected:Npn \__moloch_itemize_marker:nn #1#2
  {
    \hbox_overlap_left:n
      {
        \color_export:nnN { . } { comma-sep-rgb } \l__moloch_itemize_color_tl
        \exp_args:NnnV \definecolor { molochItemizeColor } { rgb }
          \l__moloch_itemize_color_tl
        #1
      }
    \kern -#2 \scan_stop:
  }
\cs_new_protected:Npn \__moloch_itemize_circle:
  {
    \begin{pgfpicture}
      \pgfsetfillcolor { molochItemizeColor }
      \pgfsetbaseline { -0.7ex }
      \pgfpathcircle { \pgfpoint { 0 } { 0 } } { 0.16em }
      \pgfusepath { fill }
    \end{pgfpicture}
  }
\cs_new_protected:Npn \__moloch_itemize_square:
  {
    \begin{pgfpicture}
      \pgfsetfillcolor { molochItemizeColor }
      \pgfsetbaseline { -0.7ex }
      \pgfpathrectangle
        { \pgfpoint { -0.165em } { -0.165em } }
        { \pgfpoint { 0.31em } { 0.31em } }
      \pgfusepath { fill }
    \end{pgfpicture}
  }
\cs_new_protected:Npn \__moloch_itemize_triangle:
  {
    \begin{pgfpicture}
      \pgfsetfillcolor { molochItemizeColor }
      \pgfsetbaseline { -0.7ex }
      \pgfpathmoveto { \pgfpoint { 0.21em } { 0 } }
      \pgfpathlineto { \pgfpoint { -0.21em } { 0.21em } }
      \pgfpathlineto { \pgfpoint { -0.21em } { -0.21em } }
      \pgfpathclose
      \pgfusepath { fill }
    \end{pgfpicture}
  }
\cs_set_protected:Npn \labelitemi
  { \__moloch_itemize_marker:nn { \__moloch_itemize_circle: } { 0.05ex } }
\cs_set_protected:Npn \labelitemii
  { \__moloch_itemize_marker:nn { \__moloch_itemize_square: } { 0pt } }
\cs_set_protected:Npn \labelitemiii
  { \__moloch_itemize_marker:nn { \__moloch_itemize_triangle: } { 0.25ex } }
%    \end{macrocode}
%
% \subsection{Captions}
%
% The class keeps captions unnumbered. The kernel's caption hook and label
% socket let us adjust their typography without replacing the code that tags
% the caption and its label.
%
%    \begin{macrocode}
\AddToHook { cmd / @makecaption / before } { \small }
\NewSocketPlug { caption / label } { moloch }
  { \textbf {#1} :~ }
\AssignSocketPlug { caption / label } { moloch }
%    \end{macrocode}
%
% \subsection{Title Page}
%
% The class builds its title page from a list of named elements, each of which
% is an instance of the \texttt{titlepage-element} template, and takes the
% content of an element named \texttt{x} from the macro \cs{@x}. A separator
% rule is therefore added by defining the content and declaring a matching
% instance, then naming it in the element order.
%
%    \begin{macrocode}
\tl_new:c { @titleseparator }
\tl_set:cn { @titleseparator }
  { \noindent \rule { \textwidth } { \l__moloch_titlerule_dim } }
\DeclareInstance { titlepage-element } { titleseparator } { talk }
  {
    before-skip = 0.4em ,
    after-skip = 0.8em ,
    color = mTitleseparatorFg
  }
%    \end{macrocode}
%
%    The remaining elements only need Moloch's fonts and spacing.
%
%    \begin{macrocode}
\EditInstance { titlepage-element } { title }
  { font = \Large \bfseries , color = mNormaltextFg }
\EditInstance { titlepage-element } { subtitle }
  { font = \large , color = mNormaltextFg , before-skip = 0.3em }
\EditInstance { titlepage-element } { author }
  { font = \small , before-skip = 0em , after-skip = 0.5em }
\EditInstance { titlepage-element } { institute }
  { font = \scriptsize , color = mNormaltextFg!80!mNormaltextBg }
\EditInstance { titlepage-element } { date }
  { font = \small , before-skip = 1em }
%    \end{macrocode}
%
% \begin{macro}{\__moloch_titlepage:n}
%    The \texttt{titlepage} template has no instance, so its defaults cannot be
%    edited and \cs{maketitle} has to be redefined instead.
%
%    The Beamer theme places the title block slightly above the vertical center,
%    in golden-ratio proportion. This theme uses the class's centered alignment
%    instead.
%    \begin{macrocode}
\cs_new_protected:Npn \__moloch_titlepage:n #1
  {
    \UseTemplate { titlepage } { talk }
      {
        framestyle = plain ,
        horizontal-alignment = left ,
        vertical-alignment = center ,
        element-order =
          { title , subtitle , titleseparator , author , institute , date } ,
        #1
      }
  }
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\maketitle}
%    Whether the frame environment takes a mandatory title argument depends on
%    the class option \texttt{frame-title-arg}, which is already fixed by the
%    time this package loads. The empty group is therefore inserted at
%    definition time, as the class itself does. Everything must sit in a single
%    macro body, because the frame environment collects its content up to a
%    literal \cs{end}\{frame\}.
%    \begin{macrocode}
\use:e
  {
    \exp_not:N \RenewDocumentCommand \exp_not:N \maketitle { O { } }
      {
        \exp_not:N \bool_if:NTF \exp_not:N \l__talk_frame_bool
          { \exp_not:N \__moloch_titlepage:n { \exp_not:N #1 } }
          {
            \exp_not:N \begin { frame }
              \bool_if:NT \l__talk_frame_title_bool { { } }
              \exp_not:N \__moloch_titlepage:n { \exp_not:N #1 }
            \exp_not:N \end { frame }
          }
      }
  }
%    \end{macrocode}
% \end{macro}
%
% \subsection{Section Pages}
%
% The class emits nothing at a section heading, but does provide a hook. Note
% that, unlike in Beamer, a section heading inside a frame is ignored entirely
% by the class, so a section page can only be produced from outside a frame.
%
%    \begin{macrocode}
\cs_new_protected:Npn \__moloch_section_page_body:
  {
    \thispagestyle { plain }
    \centering
    \begin { minipage } { 0.7875 \linewidth }
      \raggedright
      \color { mNormaltextFg }
      \Large \bfseries
      \insertsection
      \par
      \str_if_eq:VnT \l__moloch_sectionpage_tl { progressbar }
        {
          \skip_vertical:n { -0.5 \baselineskip }
          \__moloch_progress_rule:n { \linewidth }
        }
      % The Beamer theme always leaves a line below the bar for the
      % subsection, whether or not there is one. Keeping it means the block
      % is the same height, and so sits at the same place on the page.
      \par
      \large
      \strut
    \end { minipage }
    \par
%    \end{macrocode}
%
%    A section page carries neither the frame title band nor the footer, so
%    the block is centered on the paper rather than in the text area, which
%    is what the Beamer theme does. The frame centers its content between
%    equal glue, so a skip at the end moves the block up by half its size.
%
%    \begin{macrocode}
    \skip_vertical:n { \Gm@tmargin - \Gm@bmargin }
  }
\use:e
  {
    \exp_not:N \cs_new_protected:Npn \exp_not:N \__moloch_section_page:
      {
        \exp_not:N \begin { frame }
          [ vertical-alignment = center ]
          \bool_if:NT \l__talk_frame_title_bool { { } }
          \exp_not:N \__moloch_section_page_body:
        \exp_not:N \end { frame }
      }
  }
\AddToHook { section / begin }
  {
    \str_if_eq:VnF \l__moloch_sectionpage_tl { none }
      { \__moloch_section_page: }
  }
%    \end{macrocode}
%
% \subsection{Standout Frames}
%
% A standout frame inverts the colors and centers a short message. The class
% has no per-frame appearance option, so this is a separate environment. The
% semantic structure color follows the standout foreground so list labels
% and block titles remain visible against its background.
%
% The background cannot be set with \cs{pagecolor}: the class redefines that
% command to install a permanent background hook, so it would tint every later
% page as well. Instead a single hook is installed once, guarded by the frame
% number recorded when the standout body is typeset. The class saves this body
% for reused and supplementary frames, so they also record their current frame
% number when rendered. All slides of that frame share the same background.
%
%    \begin{macrocode}
\int_new:N \g__moloch_standout_frame_int
\int_gset:Nn \g__moloch_standout_frame_int { -1 }
%    \end{macrocode}
%
% \begin{macro}{standout}
%    \begin{macrocode}
\cs_new_protected:Npn \__moloch_standout_body:n #1
  {
    \int_gset:Nn \g__moloch_standout_frame_int { \value { frame } }
    \bool_set_true:N \l__moloch_standout_bool
    \DeclareColor { structure } { mStandoutFg }
    \color { mStandoutFg }
    \centering
    \Large \bfseries
    #1
    \par
  }
%    \end{macrocode}
%
%    The frame number is recorded globally because the body is typeset in a
%    box whose group ends before shipout. The next ordinary frame advances the
%    counter, so the hook no longer applies to it.
%
%    \begin{macrocode}
\use:e
  {
    \exp_not:N \NewDocumentEnvironment { standout }
      { !D <> { all } !O { } +b }
      {
        \exp_not:N \begin { frame } < \exp_not:N #1 >
          [ vertical-alignment = center , \exp_not:N #2 ]
          \bool_if:NT \l__talk_frame_title_bool { { } }
          \exp_not:N \__moloch_standout_body:n { \exp_not:N #3 }
        \exp_not:N \end { frame }
      }
      { }
  }
%    \end{macrocode}
% \end{macro}
%
% \subsection{Page Background and Text Color}
%
% The page-building hooks keep a frame's saved settings active through both
% the page furniture and the shipout background hooks. Their extra group
% restores the surrounding palette, page options, and page style afterward.
% A standout uses the plain style on every page, including automatic frame
% breaks.
%
%    \begin{macrocode}
\AddToHook { build / page / before }
  {
    \group_begin:
    \bool_lazy_and:nnT
      { \int_compare_p:nNn { \value { frame } } = \g__moloch_settings_frame_int }
      { \int_compare_p:nNn { \value { slide } } = \g__moloch_settings_slide_int }
      { \tl_use:N \g__moloch_frame_settings_tl }
    \int_compare:nNnT
      { \value { frame } } = \g__moloch_standout_frame_int
      { \pagestyle { plain } }
  }
\AddToHook { build / page / after } { \group_end: }
%    \end{macrocode}
%
% The page color and the default text color are set at the beginning of the
% document, so that a change of variant in the preamble is picked up.
%
% Standard color resets, including those used by minipage footnotes, must
% retain the standout foreground while its body is being typeset.
%
% The standout background hook is installed here too, and deliberately after
% the page color, so that it is applied on top of it.
%
%    \begin{macrocode}
\AddToHook { begindocument }
  {
    \pagecolor { mNormaltextBg }
    \color { mNormaltextFg }
    \renewcommand \normalcolor
      {
        \bool_if:NTF \l__moloch_standout_bool
          { \color { mStandoutFg } }
          { \color { mNormaltextFg } }
      }
    \AddToHook { shipout / background }
      {
        \int_compare:nNnT
          { \value { frame } } = \g__moloch_standout_frame_int
          {
            \put ( 0cm , -\paperheight )
              {
                \group_begin:
                  \color { mStandoutBg }
                  \rule { \paperwidth } { \paperheight }
                \group_end:
              }
          }
      }
  }
%    \end{macrocode}
%
% \iffalse
%</package>
% \fi
%
% \Finale
\endinput