The print/markdown notes that match the app.

1 · Get it running

Download, Gatekeeper, license.

Preview is free. Print, PDF, HTML export, and Export → Markdown need a key. $39, one time. No account inside the app.

1. Grab DownSide.zip (or buy first — the receipt mail includes the same link).
2. Unzip and move DownSide.app wherever you keep Mac apps. The build is Developer ID signed (AltaForma, LLC) and notarized with a stapled ticket. Gatekeeper should let it open without a right-click workaround.
3. macOS 15 or later. Apple silicon (arm64).
4. DownSide menu → License…. Email + key shaped XXXX-XXXX-XXXX-XXXX. Activate. The pair lives in Keychain, so replacing the .app does not ask again.
5. DownSide menu → Check for Updates… (Sparkle). Feed is the site appcast.xml. Automatic checks are on.

Full Disk Access is only needed if macOS blocks a protected folder (some ~/Documents / external-drive cases). Preferences → Editor has a shortcut to that pane.

Open a folder (⌘⇧O) or a file (⌘O). Multi-select in the sidebar (⌘-click / ⇧-click) hides the editor and offers Export HTML / Export PDF / Print for the selection. Files are concatenated in sidebar order with a page break between each.

3 · Print and PDF

Print Preview is the paginator. WebKit @page is not.

File → Print… (⌘P) and Export → PDF… both open Print Preview. Print… and Save as PDF… in that window go through the same paginated exporter (paper-sized snapshots). Paper size and margins are macOS Page Setup / Preferences → Print and PDF (default 0.75 inches). Print is always a light document, even if the editor preview is dark.

Tokens — header/footer chrome only

Document Setup (File → Document Setup…, or Preferences → Print and PDF) has left / center / right slots. These strings are drawn on the chrome bars, not substituted in the markdown body:

Defaults: header right {section}, footer left {title}, footer right {page}, header hidden on the first page. Page number styles: none / 1, 2, 3… / 1 of n / i, ii, iii…. Running head picker: Off / H1 / H2 / H3. First-page footer can be hidden or different. Header/footer band heights are in points.

If a job has a table of contents, ToC sheets are front matter. Their {page} uses the ToC style (i/ii/iii, I/II/III, or blank). Body page 1 starts after that section. {pages} on a ToC sheet is the front-matter count; on a body sheet it is the body count.

CSS you can actually target

Preferences → Preview: document theme (Swiss Strict default, GitHub, Academic, Manuscript, LaTeX Article, Screenplay, Wikipedia, or Custom CSS…). Optional override file. Separate choosers for syntax (Prism), Mermaid (screen), print CSS, and Mermaid print CSS. Those files apply to preview and/or Print Preview + PDF as labeled. Custom document CSS is last in the stack so the typeface can win.

Useful selectors (real class names):

#downside-body { }          /* the markdown */
#downside-body h1 { }
#downside-body pre { }
#downside-body table { }

nav.downside-toc { }
.downside-toc-title { }
.downside-toc-list { }
.downside-toc-item { }
.downside-toc-h1 { }
.downside-toc-h2 { }
.downside-toc-h3 { }
.downside-toc-link { }
.downside-toc-leaders { }
.downside-toc-page { }

#ds-print-stack { }
.ds-print-page { }
#ds-print-sheet { }
#ds-print-clip { }
.ds-print-header, #ds-print-header { }
.ds-print-footer, #ds-print-footer { }
.ds-slot.ds-left { }
.ds-slot.ds-center { }
.ds-slot.ds-right { }

.downside-print-break.downside-user-break { }
.downside-fn-ref { }
.cm-addition, .cm-deletion, .cm-highlight, .cm-comment { }

Override body text size in Document Setup if you want a point size on #downside-body that scales the print heading/table/pre sizes. Off = the CSS sizes stand.

Preferences → Print and PDF also: disable links/highlights in print (default on), optional page break before H1/H2/H3, optional --- as a page break (off by default).

5 · Diagrams / math / code

Mermaid, KaTeX, Prism. Same render as preview.

Mermaid

```mermaid
flowchart LR
  A[Notes] --> B[Print Preview]
  B --> C[PDF]
```

Fence language mermaid becomes a div.mermaid. Screen colors follow the preview theme; print/PDF always use the light Mermaid sheet (optional custom Mermaid print CSS). Don’t put Mermaid in an indented code block.

KaTeX

Delimiters that actually run: $$…$$ and \[…\] (display), \(…\) and $…$ (inline). A $ pair that is only digits/commas/spaces is skipped so currency doesn’t become math.

Inline $E = mc^2$ stays in the sentence.

$$
\int_0^1 x^2 \, dx = \tfrac{1}{3}
$$

Prism

```swift
print("hello")
```

Unknown languages still render as a language-classed pre; they just won’t get a grammar.

7 · Includes / wiki links

Both still work.

Includes

Expanded in live preview, HTML, print/PDF, and Export → Markdown. Paths are relative to the file that contains the include. The included file’s YAML is stripped. Max depth 8. Cycles and missing files become a blockquote warning, not a crash.

<<[Snippets/Colophon.md]

<!-- include Snippets/Colophon.md -->

Escape: a backslash before the angle-bracket include prints the token as literal text. Fenced code already skips includes. Backticks around the token keep it as prose.

Wiki links

Preferences → Preview → Resolve wiki links (on by default). Insert → Wiki Link wraps the selection. Double-bracket names become links. Click opens a workspace file whose stem or full name matches (case-insensitive, exact — not a slug). No match: DownSide creates that markdown file in the open folder and jumps there.

See [[Start Here]] and [[Literature Review]].

Example vault

Download the same notes.

These are the Screenshot Vault files featured on the homepage — not a roadmap, not a shot list. Open the unzipped folder in DownSide.

• Print Pipeline.md — <!-- TOC -->, <!-- BREAK -->, task list, include, footnote.
• Equations.md — KaTeX inline and display.
• Diagrams.md — Mermaid flowchart and sequence.
• Revision.md — the five CriticMarkup tokens.
• Launch Brief.md — decisions checklist and milestone table.

downside-example-vault.zip also includes Start Here.md and Snippets/Colophon.md so wiki links and includes resolve.