---
title: Reference
description: Generated and hand-written reference material — the complete utility index, every CSS custom property, and fluidity's documented limitations.
sidebar:
  label: Overview
  order: 0
---

The utility index and CSS variables pages are **generated directly from `index.css`** by `scripts/build-docs-reference.mjs`, so they can't drift from what fluidity actually ships. Limitations is hand-written from the same constraints documented in the README.

**[Utility index](/reference/utility-index)**

Every one of the 279 generated utility classes, grouped by property and curve.

**[CSS variables](/reference/css-variables)**

The 5 custom properties and 15 setter utilities that configure every ramp.

**[Limitations](/reference/limitations)**

What fluidity deliberately doesn't validate or support, and the browser baseline.