Deck Properties

The frontmatter is the block fenced by === at the very top of your .tac file. It's where you set everything that applies to the whole presentation: its title, who wrote it, what colors it uses, and which theme it follows.

===
key: value
===

Each line is a key: value pair. You can leave comments with // or # — they're ignored:

===
title: My Talk
// the brand color
accent: #FF5F1F
===

The sections below group the keys by what they do. Don't feel you need all of them — a title alone is a perfectly good frontmatter.

Metadata

These describe your presentation. They feed the automatic cover slide and the footer variables.

Key	Description
title	The deck title. Used on the cover slide and available as {title} in the footer.
subtitle	A subtitle, shown under the title on the cover.
author	The author. Appears on the cover and as {author} in the footer.
date	A date. Available as {date} in the footer.
description	An internal description. Available as {description}.

===
title: Quantum Physics — An Introduction
subtitle: Lecture 1 — Wave–particle duality
author: Prof. Ana Souza
date: 2025-06-03
===

Visual styling

These control the look of the whole deck. Behind the scenes each one sets a CSS custom property (shown in the last column), which means advanced users can also reference them in custom CSS.

Key	Also accepts	Description	Default
accent	accentColor	Accent color — titles, links, colored borders	#FF5F1F
background	bg	Slide background color or image	#ffffff
color	textColor	Main body text color	#1c1c28
headingColor	titleColor	Color of slide titles	#FF5F1F
mutedColor	—	Secondary text (subtitles, captions)	#6b7280
borderColor	—	Borders and dividers	#e5e7eb
font	fontSans	Body font family	Atkinson Hyperlegible, sans-serif
headingFont	titleFont, fontHeading	Font of titles and headings	Momo Trust Display, sans-serif
fontMono	fontCode	Code font family	JetBrains Mono, monospace
valign	verticalAlign	Vertical alignment of slide content (top/center/bottom)	center
theme	—	Built-in preset (default, dark, physics) or a .tt file	default
class	classes	Extra CSS class(es) on the root	—

The complete list

These are the everyday ones. Every key Tachyonn accepts — with synonyms, the CSS
variable behind it and its default — is in the
Property Reference.

===
title: My presentation
accent: #38bdf8
background: #0f172a
color: #e2e8f0
headingColor: #7dd3fc
font: Atkinson Hyperlegible, sans-serif
theme: ./my-theme.tt
===

Every deck already uses the built-in default theme (light, with the Tachyonn orange). Setting theme: points at your own .tt file to start from a different design.

Tips

If you only want to nudge one or two colors, you don't need a full theme. Set accent and background and you've already changed the feel of the whole deck.

The cover slide

Key	Default	Description
cover	true	Whether to auto-generate the cover slide from the frontmatter. Set to false to skip it.

===
title: Internal draft
cover: false
===

Footer

The footer has three positions — left, center, and right — each set with its own key:

===
footer.left:   {author}
footer.center: {title}
footer.right:  {page} / {total}
===

Footer values can be text (with variables like {page} and {title}) or an image. The Footer page covers this in full.

Sharing settings across files: tac.config

If your project has a file named tac.config in any parent folder, Tachyonn reads it first and then lets each file's frontmatter override it. This is perfect for giving every deck in a project the same look:

// tac.config — applies to every .tac file in this project
accent: #38bdf8
background: #0f172a
font: Atkinson Hyperlegible, sans-serif
footer.right: {page} / {total}

Any single deck can still override these by setting the same key in its own frontmatter. The order of precedence, from weakest to strongest, is:

tac.config  →  theme  →  deck frontmatter  →  per-slide frontmatter