5 ltx-talk

Warning

This part of Moloch is experimental. It targets ltx-talk, which is itself an experimental 0.x class whose author warns that “changes may occur to almost all interfaces”. Expect changes to both the class and this theme.

ltx-talk is a presentation class by Joseph Wright, built around tagged PDF. That is the main reason to prefer it over Beamer: Beamer cannot currently produce properly tagged, accessible output, and ltx-talk is designed to.

Moloch provides its design for this class through the moloch-talk package.

5.1 Requirements

Moloch is tested with ltx-talk 0.6.10, which needs a LaTeX kernel from 2026-06-01 or later. With an older kernel, you will see:

! LaTeX Error: Class ltx-talk Error: LaTeX kernel too old.

The class supports only pdflatex and lualatex. Use lualatex if you want tagged output.

5.2 Usage

Unlike Beamer, ltx-talk has no theme mechanism, and its author has said that themes are deliberately not part of its design. So there is no \usetheme here: Moloch is loaded as an ordinary package, after the class.

\DocumentMetadata{lang=en-US,tagging=on}
\documentclass{ltx-talk}
\usepackage{moloch-talk}

\title{A Minimal Example}
\subtitle{Moloch for ltx-talk}
\author{Johan Larsson}
\institute{Some University}
\date{\today}

\begin{document}

\maketitle

\section{First Section}

\begin{frame}
  \frametitle{First Frame}

  Hello, world!
\end{frame}

\begin{standout}
  Thank you!
\end{standout}

\end{document}

An example of Moloch for ltx-talk. — An example of Moloch for `ltx-talk`.

The \DocumentMetadata line is required and must come before \documentclass. Set lang to the presentation’s language and use tagging=on to enable tagged output.

The class defaults to a 16:9 aspect ratio, while Beamer defaults to 4:3. To match the Beamer demo, use \documentclass[10pt,aspect-ratio=4:3]{ltx-talk}. The slides still have different physical dimensions: ltx-talk fixes the slide height at 100mm, while Beamer’s default 4:3 slides are 96mm high.

5.3 Options

You can set options when loading the package or later with \molochset. Changes to the palette, progress bar, and frame number settings inside a frame apply to that frame. The previous settings are restored afterward.

variant [light, dark]

Selects the light or dark version of the color palette. Unlike in the Beamer theme, you can also change the palette in the middle of a document. A change inside a frame applies to its text, header, footer, and background. The previous palette is restored after the frame.

progressbar [none, head, frametitle, foot]

Adds a progress bar at the top of the slide, directly below the frame title band, or at the bottom. The bar is not drawn on the title page, on section pages, or on standout frames.

sectionpage [none, simple, progressbar]

Controls whether each \section produces a section page and whether that page carries a progress bar. The class ignores \section entirely when it appears inside a frame, so place it outside a frame to produce a section page.

framenumber [true, false]

Controls whether the frame number appears in the bottom right corner.

progressbar-linewidth [<length>] — default: 1pt

Sets the thickness of the progress bar.

titleseparator-linewidth [<length>] — default: 0.5pt

Sets the thickness of the rule between the title block and the author block on the title page.

5.4 Customization beyond these options

The option list above is deliberately short. Use the LaTeX template layer to adjust aspects of the appearance that these options do not cover. For example, to change the height of the frame title band and the font it uses:

\geometry{tmargin = 15mm, headheight = 15mm}
\EditInstance{frametitle}{header}{font = \Large\bfseries}

The palette uses ordinary color definitions. To change a color:

\definecolor{mFrametitleBg}{HTML}{4C566A}

See the ltx-talk manual for the available templates and keys.

5.4.1 Footer

Moloch uses its own footer instance, named moloch. Edit this instance to add content while keeping the theme’s margins and progress bar:

\EditInstance{footer}{moloch}{element-order={author,framenumber}}

This places the author on the left and the frame number on the right. The footer uses short metadata when available, such as the optional argument to \author. Empty elements are omitted, and framenumber=false hides the frame number without hiding other content. You can also adjust font, color, left-hspace, right-hspace, and separator, or customize each element through the class’s footer-element instances.

Captions use smaller text and bold labels while retaining the class’s unnumbered format.

Itemize lists use the same drawn markers as the Beamer theme: a filled circle, square, and triangle for the first three nesting levels. The fourth level retains the class’s default marker. Customize the markers with \renewcommand{\labelitemi}{...} (or \labelitemii and \labelitemiii), or use \item[<label>] for an individual item.

5.5 Differences from the Beamer theme

Moloch for ltx-talk is a starting point rather than a complete port of the Beamer theme. Some differences reflect features not yet implemented; others follow from the class’s design.

The title block is centered vertically. In Beamer, it sits slightly above center in golden-ratio proportion.

Moloch for ltx-talk does not yet support the following features:

The alternative color themes (tomorrow, highcontrast, catppuccin, paper). Only the default palette is available, in light and dark.
The titleformat options for small caps and capitalization.
standout=alerted and standout=example.

The class imposes the following limitations and differences from Beamer:

The frame title band’s height is fixed. Long titles wrap, but the band cannot grow to fit. Increase tmargin and headheight with \geometry when titles need more space, and increase headsep to keep the extra lines inside the band. For example, for a two-line title:
```
\geometry{tmargin=20mm,headheight=20mm,headsep=8mm}
```
\framesubtitle produces no output. The class stores the subtitle but does not currently typeset it.
Section pages and standout frames count as frames, so they advance the frame number. The Beamer theme does not count them by default.
No predefined alertblock, exampleblock, or theorem environments. Define theorem environments with \newtheorem. Blocks cannot be filled with a background color: block is a fixed environment in the class rather than a template.
No \titlegraphic. The class has no such command.
With lualatex, the class selects New Computer Modern Sans by file name, leaving no bold face registered. Bold text therefore silently appears in the regular weight. Either compile with pdflatex or set up the fonts yourself with fontspec.