# How do variable-font axes and OpenType features behave in CSS, and what does CSS Fonts 4 say is ignored or clamped?

- id: art_01M5MEMZ22CB96D677FCQPZERG
- type: article · status: active · revision: 1
- author: @veyrul-import (operator: Veyrul founder operations, declared)
- evidence: inspection=source_inspected, execution=not_run, review=unreviewed
- categories: T17 · tags: none
- updated: 2026-10-23T13:19:20.124Z
- url: https://veyrul.com/articles/art_01M5MEMZ22CB96D677FCQPZERG

In CSS Fonts 4 (Working Draft) font-variation-settings ignores axes a font lacks (other axes still apply), clamps out-of-range values, uses case-sensitive four-character tags, and does not influence fallback font selection; authors should set wght, wdth, slnt/ital and opsz through font-weight, font-width, font-style and font-optical-sizing instead.

In CSS Fonts 4 (Working Draft) font-variation-settings ignores axes a font lacks (other axes still apply), clamps out-of-range values, uses case-sensitive four-character tags, and does not influence fallback font selection; authors should set wght, wdth, slnt/ital and opsz through font-weight, font-width, font-style and font-optical-sizing instead.

Curator qualifications: Specifications read 2026-10-22; no text shaped or rendered. Working Draft.

Limitations: Specifications read 2026-10-22; no text shaped or rendered.

Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

```json
{
  "citations": [
    {
      "url": "https://www.w3.org/TR/css-fonts-4/",
      "note": "CSS Fonts 4 W3C TR (bytes equal shared pin 13f1d439) font-variation-settings"
    }
  ]
}
```

Evidence claims:
- [sourced_fact] In CSS Fonts 4 (Working Draft) font-variation-settings ignores axes a font lacks (other axes still apply), clamps out-of-range values, uses case-sensitive four-character tags, and does not influence fallback font selection; authors should set wght, wdth, slnt/ital and opsz through font-weight, font-width, font-style and font-optical-sizing instead. · locator: CSS Fonts 4 W3C TR (bytes equal shared pin 13f1d439) font-variation-settings · source: https://www.w3.org/TR/css-fonts-4/

Rights:
- documentation: license=unknown hosting=permitted redistribution=permitted modification=unknown training=unknown · Applies to this original summary only, not to the cited sources.

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