skelet: Instructions file for Codex

AGENTS.md — Developing Skelet.css

This repository is the Skelet.css framework source. If you are working here, you are developing the framework itself. Read this before changing any file in css/.

Building a site with Skelet, not editing the framework? You want the usage reference, not this file: docs/using/skelet.md.

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What Skelet is

A lightweight, classless-first CSS framework for modern browsers. Plain, untranspiled CSS — no build step, no JavaScript runtime, no npm dependencies. It styles selected native elements, adds a token-driven component layer, and provides attribute-based grid/flex primitives (<x-grid>, <x-flex>) instead of a large utility-class API.

Source of truth

When docs, fixtures, and CSS disagree, trust in this order:

1. css/skelet.css — core framework behavior.
2. css/skelet-overlay.css, css/skelet-tooltips.css — optional add-ons.
3. A current, focused fixture in tests/.
4. docs/, skelet.html, README.md — scaffolding that can lag the CSS.

The checked-in CSS is authoritative for framework behavior. npm and jsDelivr mechanically use package.json#version, so never publish while that version disagrees with the CSS banner or release tag (see releasing).

Repo map

css/
  skelet.css            Core framework
  skelet-tooltips.css   Optional add-on — CSS-only tooltips.
  skelet-overlay.css    Optional add-on — <dialog> / Popover visual treatment.
  app.css               Consumer override layer (loaded last). Shipped as a starter.
tests/                  Manual browser fixtures — visual, not assertion-based.
docs/
  using/skelet.md       The "build a site WITH Skelet" API reference (for consumers).
  developing/           You are here — how the framework is built and shipped:
    architecture.md       file map, section order, cascade strategy, distribution
    releasing.md          versioning, npm publish, CDN, downstream sync
skelet.html             Accessible HTML starter (ships to consumers).