styles-rem-not-px

styles-rem-not-px is a cursor rule for Cursor from truefoundry/trueforge. It costs 0 tokens per session (355 once invoked), scanned A, original, MIT.

Prefer rem over px for UI lengths (1rem = 16px).

Cursor rule for Cursor

Written for Cursor: installed under .cursor/.

Install with agentmods
npx agentmods add rules/truefoundry/trueforge/styles-rem-not-px
About the project

TrueForge is an agent runtime that runs the execution loop connecting language models, tools, skills, sandboxes, approvals, context handling, and session state. Developers use it through a chat interface, HTTP API, TypeScript SDK, or embeddable UI to build and operate AI agents.

truefoundry/trueforge · 5,276 stars · on GitHub · trueforge.dev

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.

Clone the repo
git clone --depth 1 https://github.com/truefoundry/trueforge

Made for: Cursor.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for styles-rem-not-px

README.md
[![agentmods](https://agentmods.dev/badge/rules/truefoundry/trueforge/styles-rem-not-px.svg)](https://agentmods.dev/rules/truefoundry/trueforge/styles-rem-not-px)
Your own site
<a href="https://agentmods.dev/rules/truefoundry/trueforge/styles-rem-not-px"><img src="https://agentmods.dev/badge/rules/truefoundry/trueforge/styles-rem-not-px.svg" alt="Measured on agentmods" height="20"></a>
Per session 0 Nothing until a file matches its globs; then the whole rule loads.
When invoked 355 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin unknown 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 5.1 $0.00000 $0.00355
Opus 5 $0.00000 $0.00178
Sonnet 5 $0.00000 $0.00071
Haiku 4.5 $0.00000 $0.00036

Measured today against content hash d3093954f434, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

styles-rem-not-px 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 today.

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.

.cursor/rules/styles-rem-not-px.mdc · 42 lines

What it actually says

Styles use rem, not px

Do not introduce CSS/Tailwind lengths in px. Use rem with 1rem = 16px.

Convert

px rem
8px 0.5rem
10px 0.625rem
11px 0.6875rem
12px 0.75rem
14px 0.875rem
16px 1rem
24px 1.5rem
32px 2rem
48px 3rem
// ❌ BAD
className="text-[10px]"
const margin = '48px';

// ✅ GOOD
className="text-[0.625rem]"
const margin = '3rem';

Prefer Tailwind spacing scale utilities (p-2, gap-1.5, text-sm) when they match; they already resolve to rem.

Allowed exceptions

  • 0px in calc() / env() fallbacks (e.g. env(safe-area-inset-bottom, 0px))
  • Media-query device breakpoints that already exist as px (e.g. (max-width: 767px)) — do not invent new px style lengths elsewhere to match them
  • Canvas / measurement APIs that require CSS pixels for drawing math
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. today First seen · 42 lines · 0 tokens per session scan A d3093954f434

Subscribe to this mod's changes

styles-rem-not-px is a cursor rule published in the GitHub repository truefoundry/trueforge (5,276 stars, last pushed today), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 355 tokens. 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 2026-09-07.