Local theme creator

Create a theme you can inspect before you copy

Adjust the palette, semantic diff colors, fonts, and window behavior while watching a live Codex preview. Validation runs locally and the theme string is written to your clipboard only when you click Copy.

Safe & local — no account, upload, or server storage.

Theme name

Theme editor

Variant

Surface

Ink

Accent

Diff added

Diff removed

Skill

Codex contrast72

UI font

Code font

Opaque windows

Live Codex preview

Codex⌘ K

You

You · now

Make the theme preview keyboard accessible.

Codex

I’ll use semantic tabs with arrow-key navigation and visible focus states.

Changed files

codex-preview.tsx+42

preview-tabs.tsx+18

Ask Codex anything…

Contrast report

Ink / Surface: 14.28:1
Accent / Surface: 4.53:1

Diff added / Surface: 4.71:1
Diff removed / Surface: 4.82:1
Skill / Surface: 5.09:1

Normal text: AA Pass · Large text: AA Pass

No contrast warnings.

All editing, validation, importing, and copying happens in this browser session. No theme string or font value is sent to analytics.