Package.json › Custom.config › does not accept modern CSS defaults like oklch in property of type color

[janpersiel]

Issue Summary

While developing a new theme I discovered that custom fields for color only accept old-school HEX values. With the wide availability of these colour schemes it would make sense to offer them in Ghost's defaults as well.

Steps to Reproduce

1. Add a custom property
   "custom": { "site_background": { "type": "color", "default": "oklch(1 0 0)" }
2. The theme fails to validate

Ghost Version

5.116.1

Node.js Version

22.14.0

How did you install Ghost?

locally, MacOS

Database type

SQLite3

Browser & OS version

No response

Relevant log / error output

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