create-theme

A guide for creating reusable house styles for open-sheet workbooks. A workbook is a spreadsheet file, and the style can define its colours, fonts, number formats, and layout conventions.

In plain words
What is it for?
Use it to create a company spreadsheet theme, define shared formatting rules, and optionally provide a demo workbook for previewing the theme.
Why use it?
It prevents each spreadsheet from developing a different visual style and makes the intended formatting readable to both people and coding agents.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/lianghsun/open-sheet/create-theme
Any agent
npx skills add lianghsun/open-sheet --skill create-theme
Clone the repo
git clone --depth 1 https://github.com/lianghsun/open-sheet

Made for: Claude Code, Codex.

Per session 61 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 456 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00061 $0.00456
Opus 5 $0.00030 $0.00228
Sonnet 5 $0.00012 $0.00091
Haiku 4.5 $0.00006 $0.00046

Measured 3d ago against content hash c45523490c7f, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

create-theme scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 3d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

packages/cli/template/skills/create-theme/SKILL.md · 57 lines

What it actually says

Create a theme

A theme is a house style that workbooks link to with meta.theme. It lives as markdown so it is readable by both people and agents.

The file

themes/<id>.md:

---
name: corporate-neutral
description: Near-white, one blue accent, sans throughout.
---

# Corporate neutral

## Palette
| Token | Value | Used for |
| --- | --- | --- |
| ink | #0f172a | body text, table header fill |
| accent | #1d4ed8 | KPI values, data bars |
| band | #f8fafc | total rows, key-value fills |
| rule | #cbd5e1 | hairlines |

## Formats
Currency `#,##0` · Percent `0.0%` · Dates `yyyy-mm-dd`

## Paste-ready design const
```tsx
export const design: DesignSystem = { … }

Conventions

  • Assumptions always on their own sheet, key-value
  • Data bars on the primary magnitude column only
  • Column widths: labels 24, figures 14

Optionally add `themes/<id>.demo.tsx` — a small workbook exercising the theme, so
the gallery has something to show.

## Rules that matter for print and Excel alike

- **One accent colour.** A second one competes; a third is decoration.
- **White or near-white background.** Anything darker costs toner and makes
  Excel's own selection highlight unreadable.
- **Body text no smaller than 10pt.** Spreadsheets get printed and squinted at.
- **Number formats are part of the theme.** A house style that leaves ratios
  unformatted has not done its job.
- Keep the `design` const a plain object literal so the Design panel can rewrite it.
Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 3d ago First seen · 57 lines · 61 tokens per session scan A c45523490c7f

Subscribe to this mod's changes

create-theme is a skill published in the GitHub repository lianghsun/open-sheet (120 stars, last pushed 7d ago), licensed MIT. It adds 61 tokens to every session and 456 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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