Galleria

---
slides: true
theme: default
paginate: true
title: The default theme
description: Marp's default theme, as a clean light deck for documentation and reports.
footer: go-slides · default theme
---

# The default theme

A clean, light deck: black text on white, a blue accent, room to breathe.

---

## Headings, lists, quotes

- Level-one and level-two headings get a rule under them
- **Bold**, *italic*, `inline code` and [links](https://github.com/go-slides/slides)
- Lists nest:
  - like this
  - and this

> A quotation is set apart by a bar on its left.

---

## Tables and code

| Theme   | Feels like     | Best for           |
| ------- | -------------- | ------------------ |
| default | a clean page   | documentation      |
| gaia    | a warm poster  | talks              |
| uncover | a calm stage   | keynotes           |

```go
func main() {
	fmt.Println("hello, slides")
}
```

---

<!-- _class: invert -->

## Invert

`<!-- _class: invert -->` flips one slide to light-on-dark, whatever the
theme. Nothing else changes.

---
slides: true
theme: gaia
paginate: true
title: The gaia theme
description: Marp's gaia theme, warm and bold, with lead slides for covers and chapter breaks.
footer: go-slides · gaia theme
---

<!-- _class: lead -->

# The gaia theme

Warm paper, strong headings, a cover slide.

---

## Content slides

Gaia sets a heavy heading over a warm background, with a coloured band on the
left of ordinary slides.

- It reads well from the back of a room
- Bullets stay short
- One idea per slide

---

<!-- _class: lead invert -->

## Lead, inverted

The `lead` class centres a slide. Add `invert` for a dark one.

---

## Spot directives

A directive with an underscore styles **this slide only**. Without it, the
directive carries on to the slides after.

```markdown
<!-- _class: lead invert -->
# One slide

<!-- class: lead -->
# This one and the next ones
```

---
slides: true
theme: uncover
paginate: true
title: The uncover theme
description: Marp's uncover theme, centred and calm, for keynote-style talks.
footer: go-slides · uncover theme
---

# The uncover theme

Centred, spacious, quiet.

---

## One thought per slide

Uncover centres its content and gives it a lot of white space. It suits few
words and big ideas.

---

<!-- _class: invert -->

## Dark when you need it

`<!-- _class: invert -->` makes this slide dark.

---

## Quotes stand out

> A slide is a sentence, not a document.

---

# Thank you

[github.com/go-slides/slides](https://github.com/go-slides/slides)

---
slides: true
theme: gaia
paginate: true
title: Slide kinds
description: A slide says what it is (title, chapter, quote) and a kinds file says how each looks.
footer: "{{ .title }} · {{ page }}/{{ total }}"
kinds: kinds/brand.yaml
---

<!-- _kind: title -->

# Slide kinds

A slide says **what** it is. A kinds file says how it looks.

---

<!-- _kind: chapter -->

# Part one

The built-in kinds, and one of ours.

---

## Built-in kinds

| Kind      | What it is                                    |
| --------- | --------------------------------------------- |
| `title`   | a cover: no header, footer or page number   |
| `section` | a chapter break                             |
| `content` | the deck's defaults                         |
| `blank`   | nothing around the content                  |

---

<!-- _kind: callout -->

## Our own kinds

The file `kinds/brand.yaml` defines `chapter`, `callout` and `quote`.
This slide is a `callout`: a warm background and a header, from one word.

---

<!-- _kind: quote -->

> Directives written by hand always win over the kind.

---

<!-- _kind: chapter -->

# Part two

Switching kinds clears what the previous kind set, so nothing leaks.

---
slides: true
theme: default
paginate: true
title: Go templates
description: Data, range loops that generate slides, page numbers and include, all before the Markdown is parsed.
footer: "{{ .team }} · {{ page }}/{{ total }}"
data:
  team: Platform team
  quarter: Q3
  releases:
    - {name: Aurora, date: "2026-07-14", highlights: [Faster builds, New CLI]}
    - {name: Borealis, date: "2026-08-25", highlights: [Plugin API, Better errors, Docs search]}
    - {name: Cirrus, date: "2026-09-29", highlights: [Windows support]}
---

# {{ .team }}: {{ .quarter }} releases

{{ len .releases }} releases this quarter, one slide each.

---

## Agenda

{{ range $i, $r := .releases }}{{ add $i 1 }}. {{ $r.name }} — {{ $r.date }}
{{ end }}
{{ range .releases }}
---

## {{ .name }}

Released {{ .date }}.

{{ range .highlights }}- {{ . }}
{{ end }}
{{ end }}
---

## What happened here

The `range` above wrote **{{ len .releases }}** slides. This one is number
**{{ page }}** of **{{ total }}**, and the deck never says so by hand.

Code stays untouched: `{{ .name }}` is shown as text, not run.

{{ include "parts/thanks.md" }}

---hcl
theme    = "uncover"
paginate = true
title    = "HCL front matter"
description = "The front matter in HCL2: expressions, functions and typed data, with the same directives as YAML."

data = {
  company = "ACME"
  quarter = 3
  growth  = [4.2, 5.1, 6.8]
}

header = format("%s — Q%d review", data.company, data.quarter)
footer = "${upper(data.company)} · ${page()}/${total()}"

kind "chapter" {
  extends = "section"
  class   = ["invert"]
}
---

# {{ .company }} Q{{ .quarter }}

Front matter written in HCL, not YAML.

---

## Expressions and functions

The header and footer above are not text, they are **expressions**:

```hcl
header = format("%s — Q%d review", data.company, data.quarter)
footer = "${upper(data.company)} · ${page()}/${total()}"
```

`page()` and `total()` are go-slides' own; the rest is HCL's standard library.

---

<!-- _kind: chapter -->

# Typed data

Numbers stay numbers, lists stay lists.

---

## Quarterly growth

{{ range $i, $g := .growth }}- Month {{ add $i 1 }}: **{{ $g }} %**
{{ end }}

`slides expand` writes this front matter back as YAML, so Marp can read the
deck too.

---
slides: true
theme: default
paginate: true
title: Math
description: Inline and display formulas, typeset to SVG at build time and identical in HTML, images and PDF.
---

# Math

`$…$` inline, `$$…$$` display. No JavaScript, no network.

---

## Inline

Einstein wrote $E = mc^2$, Euler $e^{i\pi} + 1 = 0$, and the roots of
$ax^2 + bx + c = 0$ are what the next slide is about.

A formula follows the text's size and sits on its baseline: $\alpha + \beta$,
$\sqrt{2}$, $x_{n+1}$, $\sum_{k=1}^{n} k$.

---

## The quadratic formula

$$
x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}
$$

Display formulas are centred and sized for the slide.

---

## Calculus and sums

$$
\int_{-\infty}^{\infty} e^{-x^2}\,dx = \sqrt{\pi}
\qquad
\sum_{n=1}^{\infty} \frac{1}{n^2} = \frac{\pi^2}{6}
$$

---

## Matrices

$$
A = \begin{pmatrix} 1 & 2 \\ 3 & 4 \end{pmatrix},
\qquad
\det A = 1 \cdot 4 - 2 \cdot 3 = -2
$$

---

## Prices are not math

Following Marp Core's rules, a `$` followed by a space does not open a formula
and one followed by a digit does not close it: this costs $5 and that costs
$10, and both stay text.

---
slides: true
theme: default
paginate: true
title: Images and backgrounds
description: Inline images with sizes and filters, full backgrounds, and split backgrounds.
footer: Images are original SVGs by the go-slides authors, released under CC0 1.0.
---

# Images and backgrounds

Everything on these slides is an SVG in `media/`.

![bg](media/hills.svg)

---

## An inline image, sized

![w:260](media/mark.svg)

`![w:260](media/mark.svg)` sets the width. `h:` sets the height.

---

## Filters

![w:220 grayscale](media/mark.svg) ![w:220 sepia](media/mark.svg) ![w:220 blur:4px](media/mark.svg)

`grayscale`, `sepia` and `blur:4px`, as in Marp.

---

![bg right:40%](media/grid.svg)

## A split background

```markdown
![bg right:40%](media/grid.svg)
```

The image takes the right 40% (`left` takes the left) and the text flows into the rest.

---

<!-- _class: invert -->
<!-- _footer: "" -->
<!-- _paginate: false -->

![bg](media/grid.svg)
![bg](media/hills.svg)

## Several backgrounds

Two `![bg]` images share the slide side by side.

---

![bg fit](media/mark.svg)

---

<!-- _footer: "" -->

## Attribution

`mark.svg`, `hills.svg` and `grid.svg` are original work of the go-slides
authors, released under [CC0 1.0](https://creativecommons.org/publicdomain/zero/1.0/).
You can reuse them without asking.

---
slides: true
theme: default
paginate: true
title: Code with line numbers and callouts
description: Highlighted code, optional line numbers, and numbered callouts that point at notes below the block.
---

# Code

Highlighting, line numbers and callouts.

---

## Highlighting

```go
package main

import "fmt"

func main() {
    for i := 1; i <= 3; i++ {
        fmt.Println("slide", i)
    }
}
```

Colours come from the theme, through highlight.js class names.

---

## Line numbers

```python {lineNumbers}
def fizzbuzz(n):
    for i in range(1, n + 1):
        if i % 15 == 0:
            print("FizzBuzz")
        elif i % 3 == 0:
            print("Fizz")
        elif i % 5 == 0:
            print("Buzz")
        else:
            print(i)
```

`{lineNumbers}` after the language. They are not copied with the code.

---

## Starting somewhere else

```js {lineNumbers=42}
export function clamp(x, lo, hi) {
  return Math.min(Math.max(x, lo), hi);
}
```

`{lineNumbers=42}` starts at 42, for a snippet that lives in the middle of a
file.

---

## Callouts

```go {lineNumbers}
func serve(addr string) error {
    mux := http.NewServeMux() // <1>
    mux.HandleFunc("/", home) // <2>
    return http.ListenAndServe(addr, mux) // <3>
}
```

1. A router of our own, not the global one.
2. Every request not matched elsewhere lands here.
3. Blocks until the server fails.

---

## Hover to connect

Point at a disc, or tab to it: its note lights up, and the other way round.

```sh
slides build deck.md # <1>
slides deck.md --pdf # <2>
```

1. Writes `deck.html`.
2. Writes `deck.pdf`, with vectors and selectable text.

---
slides: true
theme: gaia
paginate: true
title: Emoji and fitting headings
description: Emoji shortcodes as embedded Twemoji images, and headings that scale to fill the slide's width.
---

<!-- _class: lead -->

# <!-- fit --> Fitting headings

A fit comment in a heading makes it fill the slide's width.

---

# <!-- fit --> Short is big

---

# <!-- fit --> A longer heading shrinks to fit the same line

---

## Emoji :tada:

Shortcodes: :smile: :+1: :rocket: :heart_eyes: :books:

Unicode, too: 😄 👩‍💻 🇫🇷 1️⃣

They are Twemoji images embedded in the program, so they need no network and
look the same in the page, the images and the PDF.

---

<!-- _class: lead -->

# <!-- fit --> :sparkles: Together :sparkles:

Fitting headings and emoji combine.

---

## Turning it off

The **--no-emoji** flag leaves shortcodes and Unicode emoji as text.

In code, emoji always stay text:

```markdown
:smile: stays :smile: here
```

---
slides: true
theme: uncover
paginate: true
title: Presenting
description: Transitions between slides, speaker notes, and the presenter and overview views of the HTML page.
transition: fade 0.5s
---

# Presenting

Open this deck in a browser and press **p**.

<!--
Welcome. This note is only for you: it shows in the presenter view, never on
the slide. Press `p` for that view, `o` or Escape for the overview.
-->

---

## Speaker notes

Any HTML comment that is not a directive is a speaker note.

<!--
Notes can run several lines and use plain text.

Keep each one to what you would say, not what is on the slide.
-->

---

<!-- _transition: slide 0.6s -->

## Transitions

```markdown
<!-- transition: fade 0.5s -->
<!-- _transition: slide 0.6s -->
```

The first sets one for every slide after it, the second for this slide alone.
This one slides.

<!-- This slide has its own transition, `slide`. The others fade. -->

---

<!-- _transition: cover 0.8s -->

## 33 built in

fade, slide, cover, zoom, cube, swipe… the names are marp-cli's, played with
the browser's View Transition API.

<!-- Browsers without the API get a plain fade, and so does anyone who asked for reduced motion. -->

---

<!-- _transition: zoom 0.8s -->

## The overview

Press **o** or **Escape**: every slide in a grid. Arrow keys move, Enter goes.

<!-- The overview syncs with the presenter view. -->

---

# Thank you

<!-- Take questions here. The timer in the presenter view tells you how long you took. -->

---
slides: true
theme: gaia
paginate: true
title: Decks are code
description: A complete short talk that combines kinds, templates, math, code with callouts, images, emoji and speaker notes.
footer: "{{ .speaker }} · {{ .event }} · {{ page }}/{{ total }}"
transition: fade 0.4s
lineNumbers: true
data:
  speaker: Ada Example
  event: Slides Meetup
  principles:
    - {title: Plain text, why: "A deck is Markdown: it diffs, merges and reviews like code."}
    - {title: "One source, many outputs", why: "HTML, PDF, PPTX, ODP and images come from the same file."}
    - {title: Reproducible, why: "The same input gives the same bytes, on your laptop and in CI."}
kinds:
  chapter:
    extends: section
    class: invert
    footer: ""
  quote:
    extends: blank
    class: lead
---

<!-- _kind: title -->

![bg right:38%](media/hills.svg)

# Decks are code

{{ .speaker }}
{{ .event }}

<!--
Introduce yourself in one sentence. The point of the talk: the way we treat
code is a good way to treat slides. :tada:
-->

---

<!-- _kind: chapter -->

# Three principles

---

{{ range .principles }}
## {{ .title }}

{{ .why }}

---
{{ end }}

<!-- _kind: chapter -->

# Show, don't tell

---

## A tiny build

```sh
slides build talk.md   # <1>
slides talk.md --pdf   # <2>
slides talk.md --pptx  # <3>
```

1. The HTML page, with a presenter view on **p**.
2. A PDF with vectors and selectable text.
3. A PowerPoint file you can still edit.

<!-- Run these live if the network allows; the output files are tiny. -->

---

## Measure it

The speed-up of a parallel build on $n$ cores, with a serial fraction $s$ of
the work, is bounded by

$$
S(n) = \frac{1}{s + \frac{1 - s}{n}}
$$

so even $s = 5\%$ caps it at $20\times$.

<!-- Amdahl's law. Do not derive it; point at the cap. -->

---

<!-- _kind: quote -->

> If you can build it from a clean checkout, you can ship it.

---

<!-- _kind: title -->

# Thank you :rocket:

github.com/go-slides/slides

<!--
Pictures on these slides are original SVGs by the go-slides authors, CC0 1.0.
-->