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Semiotic

by 1amnotmad
Screenshot of the Semiotic Obsidian theme
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Code

Description

This theme supports Dark Mode
This theme supports Light Mode

README file from

Github

Semiotic

An Obsidian theme based on Ron Cobb's Semiotic Standard, the signage he designed for the USCSS Nostromo in Ridley Scott's Alien (1979).

Semiotic in light and dark mode

The light mode ("Nostromo day cycle") uses:

  • off-white padded panels and bulkhead greys
  • the signal palette taken straight from the symbols: red #a00000, grey #606060, amber #ffb000, cryo navy #0a0a70, organic green #004411
  • stenciled condensed labels
  • amber/black hazard chevrons

A dark mode ("MU-TH-UR 6000") is included as a first pass.

Screenshots

Both modes shown side by side, captured at 2× in Obsidian 1.14. Click any image for full resolution.

What it changes

Element Treatment
Callouts Every built-in callout gets a full-colour Semiotic sign as its icon (see below)
Headings Barlow Condensed, uppercase. H1 has a red rule, H2 a red marker square, H3 is signal red
Inline title Framed like a sign plate
--- rules Amber/black hazard chevrons
Checkboxes Square, red-framed
Tags Mono uppercase label plates
Tabs Squared off; the active tab has a red top edge
Sidebar Folders read as deck labels; the active file gets a red frame edge
Status bar A control-panel readout with an indicator lamp
New tab Bridge sign with the Nostromo's hull registration
Code Share Tech Mono, with syntax in the signal colours

Callouts

Built-in types

Callout Sign
note 030 Computer terminal
abstract / summary / tldr 029 Storage
info 011 Astronic system
todo 020 Direction
tip / hint / important 009 Photonic system
success / check / done 021 Life support
question / help / faq 025 Autodoc
warning / caution / attention 012 Hazard warning
failure / fail / missing 007 Non-pressurised area beyond
danger / error 017 Radiation hazard (plus a hazard band)
bug 026 Maintenance
example 024 Bridge
quote / cite 028 Intercom

Semiotic types

Every symbol is also available as its own callout:

> [!airlock] Airlock 2
> Cycle before opening.
Callout Sign Callout Sign
pressurised 001 radiation 017
gravity 002 radioactive 018
gravity-absent 003 refrigeration 019
cryo 004 direction 020
airlock 005 direction-down 020A
bulkhead 006 direction-right 020B
vacuum 007 direction-left 020C
suit-locker 008 life-support 021
photonic 009 galley 022
laser 010 coffee 023
astronic 011 bridge 024
hazard 012 autodoc 025
suit-required 013 maintenance 026
no-pressure 014 ladderway 027
exhaust 015 intercom 028
shielded 016 storage 029
storage-organic 029A
terminal 030

Each sign is also exposed as a CSS variable for your own snippets, for example:

.my-thing { background: var(--sem-icon-airlock) center / contain no-repeat; }

Install (manual)

  1. Copy manifest.json and theme.css into <vault>/.obsidian/themes/Semiotic/.
  2. In Obsidian, go to Settings → Appearance → Themes and pick Semiotic.
  3. Choose Light (recommended) or Dark as the base colour scheme.

Development

theme.css is generated. Edit the files in src/ instead:

File Contents
src/tokens.css The raw palette per mode. It's portable, so reuse it when porting the theme to other apps
src/theme.src.css The Obsidian mapping and component styling
src/icons/ Semiotic Standard SVGs
src/fonts/ Embedded woff2 fonts (Latin subset)
scripts/build.mjs Inlines the icons and fonts as data URIs, generates the callout rules, runs safety checks, and writes theme.css

To build once:

npm run build

To rebuild whenever src/ changes:

npm run watch

The build has no dependencies. Before it writes anything, it fails if the output contains:

  • !important
  • @import
  • any url() that isn't a data: URI
  • script-like constructs

This keeps the theme offline-only and overridable, as the community-theme guidelines require.

Colour roles

  • Accent follows Obsidian's accent colour setting. This covers links, checkboxes, list markers, focus rings and the caret. It defaults to signal red.
  • Signage always uses the fixed signal palette. This covers heading rules, sign-plate frames, tab and file edges, hazard stripes and the symbols.

test-vault/ holds sample notes that exercise every styled element. Its theme folder symlinks to the built files.

Credits

The Semiotic Standard symbols were designed by Ron Cobb for Alien (1979). The vector adaptations are by LouH, after Brandon Gamm, and are licensed under CC BY 4.0. Fonts are licensed under SIL OFL 1.1. See THIRD_PARTY_NOTICES.md.

The theme code is MIT licensed (see LICENSE). The symbol artwork and the embedded fonts aren't covered by the MIT licence; they keep their own licences, listed in THIRD_PARTY_NOTICES.md. This is a fan work, not affiliated with or endorsed by the rights holders of Alien.

Support

If you enjoy Semiotic, you can buy me a coffee on Ko-fi.

Support me on Ko-fi

Sponsors