Themes

Themes are defined in the form of yaml files. A few built-in themes are defined in the themes directory, but others can be created and referenced directly in every presentation.

Setting themes

There's various ways of setting the theme you want in your presentation:

CLI

Passing in the --theme parameter when running presenterm to select one of the built-in themes.

Within the presentation

The presentation's markdown file can contain a front matter that specifies the theme to use. This comes in 3 flavors:

By name

Using a built-in theme name makes your presentation use that one regardless of what the default or what the --theme option specifies:

---
theme:
  name: dark
---

By path

You can define a theme file in yaml format somewhere in your filesystem and reference it within the presentation:

---
theme:
  path: /home/me/Documents/epic-theme.yaml
---

Overrides

You can partially/completely override the theme in use from within the presentation:

---
theme:
  override:
    default:
      colors:
        foreground: "beeeff"
---

This lets you:

Create a unique style for your presentation without having to go through the process of taking an existing theme, copying somewhere, and changing it when you only expect to use it for that one presentation.
Iterate quickly on styles given overrides are reloaded whenever you save your presentation file.

A few built-in themes are bundled with the application binary, meaning you don't need to have any external files available to use them. These are packed as part of the build process as a binary blob and are decoded on demand only when used.

Currently, the following themes are supported:

dark: A dark theme.
light: A light theme.
tokyonight-storm: A theme inspired by the colors used in toyonight.
A set of themes based on the catppuccin color palette:
- catppuccin-latte
- catppuccin-frappe
- catppuccin-macchiato
- catppuccin-mocha
terminal-dark: A theme that uses your terminals color and looks best if your terminal uses a dark color scheme. This means if your terminal background is e.g. transparent, or uses an image, the presentation will inherit that.
terminal-light: The same as terminal-dark but works best if your terminal uses a light color scheme.

Trying out built-in themes

All built-in themes can be tested by using the --list-themes parameter:

presenterm --list-themes

This will run a presentation where the same content is rendered using a different theme in each slide:

Loading custom themes

On startup, presenterm will look into the themes directory under the configuration directory (e.g. ~/.config/presenterm/themes in Linux) and will load any .yaml file as a theme and make it available as if it was a built-in theme. This means you can use it as an argument to the --theme parameter, use it in the theme.name property in a presentation's front matter, etc.

Theme definition

This section goes through the structure of the theme files. Have a look at some of the existing themes to have an idea of how to structure themes.

Root elements

The root attributes on the theme yaml files specify either:

A specific type of element in the input markdown or rendered presentation. That is, the slide title, headings, footer, etc.
A default to be applied as a fallback if no specific style is specified for a particular element.

Alignment

presenterm uses the notion of alignment, just like you would have in a GUI editor, to align text to the left, center, or right. You probably want most elements to be aligned left, some to be aligned on the center, and probably none to the right (but hey, you're free to do so!).

The following elements support alignment:

Code blocks.
Slide titles.
The title, subtitle, and author elements in the intro slide.
Tables.

Left/right alignment

Left and right alignments take a margin property which specifies the number of columns to keep between the text and the left/right terminal screen borders.

The margin can be specified in two ways:

Fixed

A specific number of characters regardless of the terminal size.

alignment: left
margin:
  fixed: 5

Percent

A percentage over the total number of columns in the terminal.

alignment: left
margin:
  percent: 8

Percent alignment tends to look a bit nicer as it won't change the presentation's look as much when the terminal size changes.

Center alignment

Center alignment has 2 properties:

minimum_size which specifies the minimum size you want that element to have. This is normally useful for code blocks as they have a predefined background which you likely want to extend slightly beyond the end of the code on the right.
minimum_margin which specifies the minimum margin you want, using the same structure as margin for left/right alignment. This doesn't play very well with minimum_size but in isolation it specifies the minimum number of columns you want to the left and right of your text.

Colors

Every element can have its own background/foreground color using hex notation:

default:
  colors:
    foreground: "ff0000"
    background: "00ff00"

Default style

The default style specifies:

The margin to be applied to all slides.
The colors to be used for all text.

default:
  margin:
    percent: 8
  colors:
    foreground: "e6e6e6"
    background: "040312"

Intro slide

The introductory slide will be rendered if you specify a title, subtitle, or author in the presentation's front matter. This lets you have a less markdown-looking introductory slide that stands out so that it doesn't end up looking too monotonous:

---
title: Presenting from my terminal
sub_title: Like it's 1990
author: John Doe
---

The theme can specify:

For the title and subtitle, the alignment and colors.
For the author, the alignment, colors, and positioning (page_bottom and below_title). The first one will push it to the bottom of the screen while the second one will put it right below the title (or subtitle if there is one)

For example:

intro_slide:
  title:
    alignment: left
    margin:
      percent: 8
  author:
    colors:
      foreground: black
    positioning: below_title

The footer currently comes in 3 flavors:

None

No footer at all!

footer:
  style: empty

Progress bar

A progress bar that will advance as you move in your presentation. This will by default use a block-looking character to draw the progress bar but you can customize it:

footer:
  style: progress_bar

  # Optional!
  character: 🚀

Template

A template footer that lets you put something on the left, center and/or right of the screen. The template strings can reference {current_slide} and {total_slides} which will be replaced with the current and total number of slides.

Besides those special variables, any of the attributes defined in the front matter can also be used:

title.
sub_title.
event.
location.
date.
author.

footer:
  style: template
  left: "My name is {author}"
  center: @myhandle
  right: "{current_slide} / {total_slides}"

Slide title

Slide titles, as specified by using a setext header, has the following properties:

padding_top which specifies the number of rows you want as padding before the text.
padding_bottom which specifies the number of rows you want as padding after the text.
separator which specifies whether you want a horizontal ruler after the text (and the padding_bottom):

slide_title:
  padding_bottom: 1
  padding_top: 1
  separator: true

Headings

Every header type (h1 through h6) can have its own style composed of:

The prefix you want to use.
The colors, just like any other element:

headings:
  h1:
    prefix: "██"
    colors:
      foreground: "rgb_(48,133,195)"
  h2:
    prefix: "▓▓▓"
    colors:
      foreground: "rgb_(168,223,142)"

Code blocks

The syntax highlighting for code blocks is done via the syntect crate. The list of all the supported built-in syntect themes is the following:

base16-ocean.dark
base16-eighties.dark
base16-mocha.dark
base16-ocean.light
InspiredGitHub
Solarized (dark)
Solarized (light)

Besides those and thanks to the work done on the awesome bat tool, presenterm has access to not only the built-in syntect's built-in themes but also the ones in bat. Run bat --list-themes to see a list of all of them.

Code blocks can also have an optional vertical and horizontal padding so your code is not too close to its bounding rectangle:

code:
  theme_name: base16-eighties.dark
  padding:
    horizontal: 2
    vertical: 1

Custom highlighting themes

Besides the built-in highlighting themes, you can drop any .tmTheme theme in the themes/highlighting directory under your configuration directory (e.g. ~/.config/presenterm/themes/highlighting in Linux) and they will be loaded automatically when presenterm starts.

Block quotes

For block quotes you can specify a string to use as a prefix in every line of quoted text:

block_quote:
  prefix: "▍ "

Mermaid

The mermaid graphs can be customized using the following parameters:

mermaid.background the background color passed to the CLI (e.g., transparent, red, #F0F0F0).
mermaid.theme the mermaid theme to use.

mermaid:
  background: transparent
  theme: dark

Extending themes

Custom themes can extend other custom or built in themes. This means it will inherit all the properties of the theme being extended by default.