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chore: import upstream snapshot with attribution

2026-07-13 12:40:49 +08:00

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Codex Design System Notes

These notes describe the inspected Codex desktop app, not Codium's implementation. The source snapshot was taken from the running macOS Codex app via the Chrome DevTools Protocol on app://-/index.html?hostId=local.

Observed app version:

App title: Codex
User agent: Codex/26.422.30944 Chrome/146.0.7680.179 Electron/41.2.0
Theme class: electron-dark
Viewport sampled: 1344 x 877

Theming Pipeline (reverse-engineered)

Codex generates ~149 CSS custom properties from 5 atomic user inputs per theme, via a JS pre-pass that writes derived values onto <html>'s inline style, plus a CSS layer that resolves the rest with color-mix(in oklab, …).

Inputs (per theme — `Light`, `Dark`)

The user-editable theme object is persisted to ~/.codex/.codex-global-state.json under electron-persisted-atom-state.appearance{Light,Dark}ChromeTheme:

{
  "accent":   "#0169cc",       // link/highlight color
  "ink":      "#0d0d0d",       // foreground text/icon color
  "surface":  "#ffffff",       // primary surface color
  "contrast": 40,              // 0–100 — single shaping knob
  "fonts":    { "ui": "Geist, Inter", "code": "\"Geist Mono\", ui-monospace, ..." },
  "opaqueWindows": true,       // light=true, dark=false (vibrancy)
  "semanticColors": {
    "diffAdded":   "#00a240",
    "diffRemoved": "#e02e2a",
    "skill":       "#751ed9"
  }
}

appearanceTheme (top-level) selects the resolved mode: "light" | "dark" | "system". system queries nativeTheme.shouldUseDarkColors.

Resolution flow

Resolve mode → pick the matching appearance{Light,Dark}ChromeTheme object.
Set <html> class:
- electron-light or electron-dark (resolved theme)
- + electron-opaque if opaqueWindows: true (Tailwind variant trigger)

Inline-style <html> with the 5 base values verbatim:

--codex-base-accent:   <accent>;
--codex-base-ink:      <ink>;
--codex-base-surface:  <surface>;
--codex-base-contrast: <contrast>;
--vscode-font-family:        <fonts.ui>;
--vscode-editor-font-family: <fonts.code>;

JS pre-pass writes ~80 derived hex/rgba values onto the same inline style, so most tokens are concrete colors at runtime.
CSS rules add ~70 more tokens via color-mix(in oklab, var(--color-text-foreground) X%, transparent) etc., for the constant-alpha overlays.

The shaping function

Every contrast-driven token has the form:

value(contrast) = base + delta · t(contrast)

Where t(0) = 0, t(100) = 1, and t(c) = (c/100)^p. Fitting 9 different alpha tokens against the same shaping function yields tightly clustered exponents:

Light theme: p ≈ 1.50
Dark theme: p ≈ 1.66

Dark uses a slightly steeper curve, presumably to compensate for vibrancy compositing reducing perceptual contrast on translucent surfaces. Each token defines its own (base, delta) pair; the curve t(c) is shared across all of them.

Token derivation buckets

Bucket	Behavior	Example tokens	Formula
A. Pass-through	Literal copy of an input	`--color-text-foreground = ink`, `--color-background-surface = surface`, `--color-text-accent = accent` (light only)	`value = input`
B. Static-alpha ink overlays	Constant alpha, contrast-independent	`--color-token-list-hover-background` (5%), `--color-token-bg-fog` (2.5%), `--color-token-badge-background` (4.7%), `--color-token-input-border` (7.4%)	`rgba(ink, k)` — k is per-token constant
C. Contrast-shaped ink overlays	`rgba(ink, …)` ramped by contrast	`--color-border` (0.04 → 0.17), `--color-text-foreground-secondary` (0.60 → 0.93), `--color-background-button-primary-active` (0.04 → 0.44), `--color-icon-secondary`, `--color-text-foreground-tertiary`	`rgba(ink, base + delta · t(c))`
D. Surface ↔ ink mixes	Slight tint of surface toward ink	`--color-background-surface-under` (sidebar/page bg)	`mix(surface, ink, base + delta · t(c))`
E. Surface ↔ accent mixes	Pale accent backgrounds (selection/hover)	`--color-background-accent`, `--color-background-accent-hover`, `--color-background-accent-active`	`mix(surface, accent, base + delta · t(c))`

In dark mode only, --color-text-accent is itself a contrast-shaped mix toward ink (= white):

text-accent_dark(c) = mix(accent, ink, 0.19 + 0.46 · t(c))

This auto-lightens the user-supplied accent (e.g. #339cff) toward white for legibility against #181818. Light mode leaves accent as a pass-through.

Empirical token table (light theme, `ink=#0d0d0d`, `surface=#ffffff`, `accent=#0169cc`)

Token	c=0	c=40	c=100	Formula
`--color-text-foreground`	`#0d0d0d`	`#0d0d0d`	`#0d0d0d`	`ink`
`--color-background-surface`	`#ffffff`	`#ffffff`	`#ffffff`	`surface`
`--color-background-surface-under`	`#ffffff`	`#f7f7f7`	`#e5e5e5`	`mix(surface, ink, 0.10·t(c))`
`--color-text-foreground-secondary`	`rgba(13,13,13,0.598)`	`rgba(…,0.684)`	`rgba(…,0.933)`	`rgba(ink, 0.60 + 0.34·t(c))`
`--color-text-foreground-tertiary`	`rgba(…,0.398)`	`rgba(…,0.484)`	`rgba(…,0.733)`	`secondary − 0.20` (constant offset)
`--color-border`	`rgba(…,0.039)`	`rgba(…,0.074)`	`rgba(…,0.173)`	`rgba(ink, 0.04 + 0.13·t(c))`
`--color-border-heavy`	`rgba(…,0.059)`	`rgba(…,0.111)`	`rgba(…,0.260)`	`rgba(ink, 0.06 + 0.20·t(c))`
`--color-background-button-primary-active`	`rgba(…,0.037)`	`rgba(…,0.141)`	`rgba(…,0.440)`	`rgba(ink, 0.04 + 0.40·t(c))`
`--color-background-accent`	`#e8f2fa`	`#e0ecf9`	`#c6def4`	`mix(surface, accent, 0.09 + 0.13·t(c))`
`--color-token-list-hover-background`	`rgba(…,0.05)`	`rgba(…,0.05)`	`rgba(…,0.05)`	`rgba(ink, 0.05)` (constant)
`--color-token-bg-fog`	`mix(oklab, ink 2.5%, transparent)`	same	same	constant alpha, CSS-only

Effects of changing each input

Input	Tokens affected
`accent`	Only the accent family (`text-accent`, `icon-accent`, `bg-accent`, `bg-accent-hover`, `bg-accent-active`) — ~6 tokens. Borders and ink overlays don't shift.
`ink`	Most tokens — every `rgba(ink, α)` overlay plus surface↔ink mixes. Setting `ink: #ff0000` recolors borders, secondary text, fog, hover, etc., and tints `surface-under` toward red.
`surface`	`background-surface` directly, plus all surface mixes (`surface-under`, `bg-accent` family, `dropdown`, `input-background`).
`contrast`	Only the contrast-shaped tokens (~25). Static-alpha overlays don't move.
`opaqueWindows`	Toggles vibrancy: light = opaque body, dark = `body { background: color(srgb 0.157 0.157 0.157 / 0.55) }` so macOS vibrancy shows through. Adds/removes `electron-opaque` class.

Design ideas

Few inputs, many outputs. A theme is a small JSON; designers pick 3 colors + 1 slider; "Copy theme" / "Import" exchange the JSON.
Single shaping curve per theme. Contrast isn't 25 knobs — it's one t(c) = (c/100)^p applied to every contrast-driven token. Per-token (base, delta) is the only thing that varies.
Ink as an alpha source. Dividers/secondary text/hover are rgba(ink, α), not literal greys. Auto-flips with theme; works with custom ink colors; keeps perceptual contrast consistent.
Accent stays on its own track. Changing accent never recolors general tokens — only the explicit accent family. Custom themes can't go chaotic.
Constant-alpha for ambient, contrast-shaped for interactive. Fog/list-hover are quiet across the slider; borders/button states get punchier as the user dials contrast up — exactly what the slider name implies.
Two-tier compute. Heavy precomputed colors live in JS-injected inline style; light constant-alpha overlays stay in CSS via color-mix(in oklab, …) so they hot-recompute when ink changes.
Theme-aware accent legibility. Dark mode auto-mixes accent toward white as contrast increases, so users can pick any accent hue without worrying about contrast failures on #181818.
Semantic colors are literal. diffAdded/diffRemoved/skill bypass the derivation pipeline — they're direct inputs because diff red and OK green need to mean what they mean.

Token Counts

When the renderer settles, getComputedStyle(:root) reports ~149 reachable custom properties. They split as:

Layer	Count	Source
Inline-style chrome tokens	65	Computed in JS by `deriveTokens()` and written to `<html>.style`
`--color-token-*` design-system aliases	96	CSS-only, `var()` references to inline tokens
Other (fonts, Tailwind base palette, VS Code editor tokens)	~700	Unrelated to chrome theme; bundled VS Code editor / framework defaults

The 65 + 96 ≈ 161 surface that chrome components actually consume.

Built-in Themes Catalog

Codex's app.asar bundles ~70 theme files. They split into two kinds based on what they export, and both kinds end up as selectable themes in the UI.

Kind 1 — first-class chrome themes (12 files)

These export a fully-formed chromeTheme object next to their VS Code-style colors object. They were authored explicitly for Codex's chrome — designer chose every input by hand:

// e.g. linear-dark.js
export const chromeTheme = {
    accent:   '#5e6ad2',
    contrast: 60,
    fonts:    { ui: 'Inter', code: null },
    ink:      '#e3e4e6',
    opaqueWindows: true,
    semanticColors: {
        diffAdded:   '#69c967',
        diffRemoved: '#ff7e78',
        skill:       '#c2a1ff',
    },
    surface: '#0f0f11',
}

Bundled themes of this kind: Linear Dark/Light, Vercel Dark/Light, Raycast Dark/Light, Notion Dark/Light, Sentry Dark, Lobster Dark, Matrix Dark, Proof Light (12 entries). Plus the codex default in appearance{Light,Dark}ChromeTheme on the persistent global state file (counts as 2 more).

The chrome theme object can be a partial — Codex merges it on top of the codex default for the same variant. Lobster, Matrix, Notion, Proof, and Sentry only override fonts and/or opaqueWindows and inherit everything chromatic from the codex default.

Kind 2 — VS Code code themes (~55 files)

The rest are pure VS Code colorTheme JSONs (Dracula, Tokyo Night, Catppuccin, One Dark Pro, Gruvbox, Monokai, Nord, Solarized, Material Theme, etc.). They define editor / activity-bar / terminal colors but don't carry a chromeTheme object:

// e.g. dracula.js
{
    "editor.background": "#282A36",
    "editor.foreground": "#F8F8F2",
    "focusBorder":       "#bd93f9",
    "activityBar.activeBorder": "#bd93f9",
    "terminal.ansiBlue": "#bd93f9",
    /* …50+ more editor.* / activityBar.* / terminal.* fields… */
}

When the user picks one of these from the code-theme picker, Codex synthesizes a chrome theme on the fly from the VS Code colors. The mapping is:

Chrome input	Source field (first non-null wins)	Notes
`surface`	`editor.background`	The dominant background color of the editor pane.
`ink`	`editor.foreground`	The primary text color.
`accent`	`focusBorder` → `activityBar.activeBorder` → `editorCursor.foreground` → `terminal.ansiBlue` → `button.background`	Pick the first that's non-transparent and ≠ surface. Themes whose `focusBorder` is `#XXXXXX00` (alpha 0) fall through to the next candidate.
`contrast`	(codex default for variant)	45 light / 60 dark.
`opaqueWindows`	(codex default for variant)	`false` for both — code themes don't author this.
`fonts`	(codex default)	Geist UI + Geist Mono code.
`semanticColors.diffAdded`	(codex default for variant)	`#00a240` light / `#40c977` dark.
`semanticColors.diffRemoved`	(codex default)	`#ba2623` / `#fa423e`.
`semanticColors.skill`	(codex default)	`#924ff7` / `#ad7bf9`.

The synthesized chrome theme then runs through the same deriveTokens() pipeline as a first-class chrome theme — there's no separate code path.

Catalog (Codium ships)

Kind	Source	Count
Codex defaults	`appearance{Light,Dark}ChromeTheme` global state	2
First-class chrome themes	bundled `chromeTheme` exports	12
Code-theme-derived	synthesized from `editor.*` / `focusBorder`	55
Total		69

Limitations of synthesis

A code theme can't communicate the things that don't live in its color table:

Contrast — the editor.* JSON has no equivalent of the contrast knob, so all 55 derived themes start at the codex default contrast (45 / 60). The user can still adjust it in Settings → Appearance.
opaqueWindows — same: no signal for whether the window should be opaque vs translucent. Defaults to false (vibrancy on).
Fonts — code themes don't ship UI/code font preferences; we use the codex defaults. (Codex's first-class chrome themes like Linear sometimes do override fonts — Inter for Linear, Satoshi for Lobster.)
Diff / skill colors — these are intentionally meaningful (red-must-mean-error, green-must-mean-added) and code themes don't always agree on them, so we always use the codex default semantic colors.

If you want a more faithful version of any synthesized theme, override the relevant inputs by hand — the chrome theme is just a JSON, persisted to localStorage by applyPreset().

JS Derivation Functions

The runtime functions that compute the 65 inline tokens. Pseudocode pulled from the running app, normalized to the names used in packages/codium/sources/theme/derive.ts.

Inputs

type ChromeTheme = {
    accent:   string   // hex
    ink:      string   // hex (foreground)
    surface:  string   // hex (primary surface)
    contrast: number   // 0..100
    opaqueWindows: boolean
    fonts: { ui: string | null, code: string | null }
    semanticColors: { diffAdded: string, diffRemoved: string, skill: string }
}

type ThemeMode = 'light' | 'dark'

Color helpers

type RGB = [number, number, number]

const parseHex = (h: string): RGB => …          // '#0d0d0d' → [13, 13, 13]
const rgbToHex = (rgb: RGB): string => …        // [13, 13, 13] → '#0d0d0d'
const rgba     = (rgb: RGB, a: number): string  // → 'rgba(13, 13, 13, 0.123)'
const rgb      = (rgb: RGB): string             // → 'rgb(13, 13, 13)'

// Standard sRGB linear interpolation (the running app does NOT use oklab here
// for the JS-side mixes; it only uses oklab for the CSS-side `color-mix`).
const mix = (a: RGB, b: RGB, t: number): RGB => [
    a[0] * (1 - t) + b[0] * t,
    a[1] * (1 - t) + b[1] * t,
    a[2] * (1 - t) + b[2] * t,
]

const BLACK: RGB = [0, 0, 0]
const WHITE: RGB = [255, 255, 255]

Shaping function

The contrast slider is a single non-linear knob applied to every contrast-driven token. Each mode has its own exponent.

const shape = (contrast: number, mode: ThemeMode): number => {
    const c = clamp01(contrast / 100)
    const p = mode === 'dark' ? 1.66 : 1.50
    return Math.pow(c, p)
}

const apply = (curve: { base: number, delta: number }, t: number) =>
    curve.base + curve.delta * t

Per-token coefficient table

Empirically fit from snapshots of the running Codex app.

const COEFFS: Record<ThemeMode, ModeCoeffs> = {
    light: {
        p: 1.5,
        fgSecondary:          { base: 0.598, delta: 0.335 },
        fgTertiary:           { base: 0.398, delta: 0.335 },
        border:               { base: 0.04,  delta: 0.133 },
        borderHeavy:          { base: 0.06,  delta: 0.20  },
        borderLight:          { base: 0.03,  delta: 0.067 },
        iconPrimary:          'passthrough',           // light: ink as-is
        btnPrimaryActive:     { base: 0.04,   delta: 0.40  },
        btnPrimaryHover:      { base: 0.02,   delta: 0.20  },
        btnPrimaryInactive:   { base: 0.151,  delta: 0.306 },
        btnSecondary:         { base: 0.037,  delta: 0.041 },
        btnSecondaryActive:   { base: 0.027,  delta: 0.041 },
        btnSecondaryHover:    { base: 0.035,  delta: 0.061 },
        btnSecondaryInactive: { base: 0.007,  delta: 0.041 },
        btnTertiary:          { base: 0,      delta: 0     }, // always transparent
        btnTertiaryActive:    { base: 0.140,  delta: 0.184 },
        btnTertiaryHover:     { base: 0.073,  delta: 0.082 },
        surfUnder:            { base: 0.0,    delta: 0.10  },  // mix(surface, ink)
        bgAccent:             { base: 0.09,   delta: 0.13  },  // mix(surface, accent)
        bgAccentHover:        { base: 0.10,   delta: 0.15  },
        bgAccentActive:       { base: 0.11,   delta: 0.16  },
        accentForegroundMix:  { base: 0,      delta: 0     },  // light: passthrough
        accentPurple:         '#751ed9',
        decorationAdded:      '#00a240',
        decorationDeleted:    '#e02e2a',
        editorOverlayAlpha:   0.15,
    },
    dark: {
        p: 1.66,
        fgSecondary:          { base: 0.58,  delta: 0.303 },
        fgTertiary:           { base: 0.329, delta: 0.394 },
        border:               { base: 0.032, delta: 0.121 },
        borderHeavy:          { base: 0.078, delta: 0.182 },
        borderLight:          { base: 0.016, delta: 0.061 },
        iconPrimary:          { base: 0.79,  delta: 0.27  },
        btnPrimaryActive:     { base: 0.035, delta: 0.152 },
        btnPrimaryHover:      { base: 0.019, delta: 0.091 },
        btnPrimaryInactive:   { base: 0.017, delta: 0.036 },
        btnSecondary:         { base: 0.037, delta: 0.036 },
        btnSecondaryActive:   { base: 0.078, delta: 0.099 },
        btnSecondaryHover:    { base: 0.051, delta: 0.063 },
        btnSecondaryInactive: { base: 0.015, delta: 0.054 },
        btnTertiary:          { base: 0.017, delta: 0.027 },
        btnTertiaryActive:    { base: 0.058, delta: 0.099 },
        btnTertiaryHover:     { base: 0.041, delta: 0.063 },
        surfUnder:            { base: 0.05,  delta: 0.16 },   // mix(surface, BLACK)
        bgAccent:             { base: 0.17,  delta: 0.19 },   // mix(BLACK, accent)
        bgAccentHover:        { base: 0.18,  delta: 0.21 },
        bgAccentActive:       { base: 0.20,  delta: 0.23 },
        accentForegroundMix:  { base: 0.19,  delta: 0.46 },
        accentPurple:         '#ad7bf9',
        decorationAdded:      '#40c977',
        decorationDeleted:    '#fa423e',
        editorOverlayAlpha:   0.23,
    },
}

// Dark-mode-only "above surface" mixes (no headroom in light because
// surface is already at maximum brightness).
const DARK_SURFACE_MIX = {
    controlOpaque:     { base: 0.049, delta: 0.099 },  // mix(surface, ink, …)
    editorOpaque:      { base: 0.058, delta: 0.027 },  // mix(surface, ink, …)
    elevatedPrimary:   { base: 0.053, delta: 0.180 },  // mix(surface, ink, …)
    buttonPrimaryFill: { base: 0.46,  delta: 0     },  // mix(surface, BLACK, …)
    textBtnSecondary:  { base: 0.20,  delta: 0.09  },  // mix(surface, ink, …)
}

Main derivation

function deriveTokens(theme: ChromeTheme, mode: ThemeMode): Record<string, string> {
    const ink     = parseHex(theme.ink)
    const surface = parseHex(theme.surface)
    const accent  = parseHex(theme.accent)
    const t = shape(theme.contrast, mode)
    const C = COEFFS[mode]

    const inkA       = (alpha: number) => rgba(ink, alpha)
    const inkOverlay = (curve: Curve)  => inkA(apply(curve, t))

    // — accent foreground (legibility)
    const accentFg = mode === 'dark'
        ? rgbToHex(mix(accent, WHITE, apply(C.accentForegroundMix, t)))
        : theme.accent

    // — surface "below" (page / sidebar bg) — quieter than surface in both modes
    const surfaceUnder = rgbToHex(mix(
        surface,
        mode === 'dark' ? BLACK : ink,
        apply(C.surfUnder, t),
    ))

    // — surface "above" (panel / elevated / control / editor)
    const above = mode === 'dark'
        ? {
            control:  mix(surface, ink, apply(DARK_SURFACE_MIX.controlOpaque,  t)),
            editor:   mix(surface, ink, apply(DARK_SURFACE_MIX.editorOpaque,   t)),
            elevated: mix(surface, ink, apply(DARK_SURFACE_MIX.elevatedPrimary, t)),
        }
        : { control: surface, editor: surface, elevated: surface }

    // — bg-accent family (selection / hover accent)
    const bgAccentBase = mode === 'dark' ? BLACK : surface
    const bgAccentRgb       = mix(bgAccentBase, accent, apply(C.bgAccent,        t))
    const bgAccentHoverRgb  = mix(bgAccentBase, accent, apply(C.bgAccentHover,   t))
    const bgAccentActiveRgb = mix(bgAccentBase, accent, apply(C.bgAccentActive,  t))

    // — primary button fill
    const buttonPrimaryFill = mode === 'dark'
        ? mix(surface, BLACK, apply(DARK_SURFACE_MIX.buttonPrimaryFill, t))
        : ink

    return {
        // base inputs (echoed)
        '--codex-base-accent':   theme.accent,
        '--codex-base-ink':      theme.ink,
        '--codex-base-surface':  theme.surface,
        '--codex-base-contrast': String(theme.contrast),

        // fonts
        '--vscode-font-family':        appendFontFallback(theme.fonts.ui   ?? 'Geist, Inter',                                  'sans'),
        '--vscode-editor-font-family': appendFontFallback(theme.fonts.code ?? '"Geist Mono", ui-monospace, "SFMono-Regular"',  'mono'),

        // typography (fixed; not theme-dependent)
        '--text-xs': '11px', '--text-sm': '12px', '--text-base': '13px', '--text-lg': '16px',
        '--text-heading-sm': '18px', '--text-heading-md': '20px', '--text-heading-lg': '24px',
        '--text-xl': '28px', '--text-2xl': '36px', '--text-3xl': '48px', '--text-4xl': '72px',
        '--vscode-font-size': '13px', '--vscode-editor-font-size': '12px',

        // pass-throughs / accent
        '--color-text-foreground':    theme.ink,
        '--color-icon-primary':       C.iconPrimary === 'passthrough' ? theme.ink : inkA(apply(C.iconPrimary, t)),
        '--color-text-accent':        accentFg,
        '--color-icon-accent':        accentFg,
        '--color-background-surface': theme.surface,
        '--color-accent-blue':        theme.accent,
        '--color-accent-purple':      C.accentPurple,

        // static-alpha ink overlays
        '--color-hover':                          inkA(0.05),
        '--color-token-list-hover-background':    inkA(0.05),
        '--color-token-toolbar-hover-background': inkA(0.05),
        '--color-token-badge-background':         inkA(0.047),
        '--color-token-input-border':             inkA(0.074),
        '--color-token-bg-fog':                   inkA(0.025),

        // contrast-shaped ink overlays
        '--color-text-foreground-secondary':            inkOverlay(C.fgSecondary),
        '--color-text-foreground-tertiary':             inkOverlay(C.fgTertiary),
        '--color-icon-secondary':                       inkOverlay(C.fgSecondary),
        '--color-icon-tertiary':                        inkOverlay(C.fgTertiary),
        '--color-border':                               inkOverlay(C.border),
        '--color-border-heavy':                         inkOverlay(C.borderHeavy),
        '--color-border-light':                         inkOverlay(C.borderLight),
        '--color-active':                               inkA(0.04 + 0.06 * t),
        '--color-button-bg':                            inkA(0.04 + 0.06 * t),
        '--color-button-hover':                         inkA(0.04 + 0.04 * t),

        // simple-scrim: BLACK in light, INK in dark
        '--color-simple-scrim': mode === 'light'
            ? rgba(BLACK, 0.06 + 0.13 * t)
            : inkA(0.06 + 0.13 * t),

        // button background family
        '--color-background-button-primary':            mode === 'dark' ? rgb(buttonPrimaryFill) : rgbToHex(buttonPrimaryFill),
        '--color-background-button-primary-active':     inkOverlay(C.btnPrimaryActive),
        '--color-background-button-primary-hover':      inkOverlay(C.btnPrimaryHover),
        '--color-background-button-primary-inactive':   inkOverlay(C.btnPrimaryInactive),
        '--color-background-button-secondary':          inkOverlay(C.btnSecondary),
        '--color-background-button-secondary-active':   inkOverlay(C.btnSecondaryActive),
        '--color-background-button-secondary-hover':    inkOverlay(C.btnSecondaryHover),
        '--color-background-button-secondary-inactive': inkOverlay(C.btnSecondaryInactive),
        '--color-background-button-tertiary':           inkOverlay(C.btnTertiary),
        '--color-background-button-tertiary-active':    inkOverlay(C.btnTertiaryActive),
        '--color-background-button-tertiary-hover':     inkOverlay(C.btnTertiaryHover),

        // text on buttons
        '--color-text-button-primary':   mode === 'dark' ? rgb(buttonPrimaryFill) : theme.surface,
        '--color-text-button-secondary': mode === 'dark'
            ? rgbToHex(mix(surface, ink, apply(DARK_SURFACE_MIX.textBtnSecondary, t)))
            : theme.ink,
        '--color-text-button-tertiary':  inkOverlay(C.fgTertiary),

        // surface family
        '--color-background-surface-under':             surfaceUnder,
        '--color-background-panel':                     mode === 'dark' ? rgbToHex(mix(surface, ink, 0.07)) : theme.surface,
        '--color-background-control':                   rgba(above.control, 0.96),
        '--color-background-control-opaque':            rgb(above.control),
        '--color-background-editor-opaque':             rgb(above.editor),
        '--color-background-elevated':                  rgba(above.elevated, 0.96),
        '--color-background-elevated-primary':          rgba(above.elevated, 0.96),
        '--color-background-elevated-primary-opaque':   rgb(above.elevated),
        '--color-background-elevated-secondary':        mode === 'dark' ? inkOverlay(C.btnPrimaryInactive) : rgba(surface, 0.96),
        '--color-background-elevated-secondary-opaque': rgbToHex(above.editor),

        // accent backgrounds
        '--color-background-accent':         rgbToHex(bgAccentRgb),
        '--color-background-accent-hover':   rgbToHex(bgAccentHoverRgb),
        '--color-background-accent-active':  rgbToHex(bgAccentActiveRgb),

        // focus ring
        '--color-border-focus': mode === 'dark'
            ? rgba(parseHex(accentFg), 0.76)
            : theme.accent,

        // fixed brand: diff / editor overlays
        '--color-decoration-added':   C.decorationAdded,
        '--color-decoration-deleted': C.decorationDeleted,
        '--color-editor-added':       rgba(parseHex(C.decorationAdded),   C.editorOverlayAlpha),
        '--color-editor-deleted':     rgba(parseHex(C.decorationDeleted), C.editorOverlayAlpha),

        // legacy semantic-color shortcuts
        '--color-accent-green': theme.semanticColors.diffAdded,
        '--color-accent-red':   theme.semanticColors.diffRemoved,
    }
}

Apply to the document

function applyTheme(theme: ChromeTheme, mode: ThemeMode) {
    const root = document.documentElement
    for (const [k, v] of Object.entries(deriveTokens(theme, mode))) {
        root.style.setProperty(k, v)
    }
    root.classList.toggle('electron-light',  mode === 'light')
    root.classList.toggle('electron-dark',   mode === 'dark')
    root.classList.toggle('electron-opaque', !!theme.opaqueWindows)
    root.style.colorScheme = mode
}

CSS-Side Aliases

Codex defines ~96 --color-token-* design-system aliases in CSS that reference the inline-injected tokens. Components consume these via Tailwind utilities (e.g. bg-token-input-background, text-token-foreground).

They live in CSS so they hot-recompute when an inline token changes — no JS re-derive needed. Most are var() references; a few are color-mix() derivations; status/error/charts colors are fixed brand colors per mode.

:root {
    /* text aliases */
    --color-token-foreground:                            var(--color-text-foreground);
    --color-token-text-primary:                          var(--color-text-foreground);
    --color-token-text-secondary:                        var(--color-text-foreground-secondary);
    --color-token-text-tertiary:                         var(--color-text-foreground-tertiary);
    --color-token-description-foreground:                var(--color-text-foreground-tertiary);
    --color-token-disabled-foreground:                   var(--color-text-foreground-tertiary);

    /* icon */
    --color-token-icon-foreground:                       var(--color-icon-primary);

    /* surface / background */
    --color-token-main-surface-primary:                  var(--color-background-surface);
    --color-token-bg-primary:                            var(--color-background-surface-under);
    --color-token-bg-secondary:                          color-mix(in srgb, var(--color-background-surface-under) 92%, transparent);
    --color-token-bg-tertiary:                           color-mix(in srgb, var(--color-background-surface-under) 85%, transparent);
    --color-token-side-bar-background:                   var(--color-background-surface-under);
    --color-token-input-background:                      var(--color-background-control);
    --color-token-dropdown-background:                   var(--color-background-elevated-primary-opaque);
    --color-token-menu-background:                       var(--color-background-elevated-primary);
    --color-token-checkbox-background:                   var(--color-background-elevated-primary);
    --color-token-bg-fog:                                color-mix(in oklab, var(--color-text-foreground) 2.5%, transparent);

    /* input / checkbox / menu */
    --color-token-input-foreground:                      var(--color-text-foreground);
    --color-token-input-placeholder-foreground:          var(--color-text-foreground-tertiary);
    --color-token-input-border:                          var(--color-border);
    --color-token-checkbox-foreground:                   var(--color-text-foreground);
    --color-token-checkbox-border:                       var(--color-border);
    --color-token-menu-border:                           var(--color-border);
    --color-token-menubar-selection-foreground:          var(--color-text-foreground);
    --color-token-menubar-selection-background:          var(--color-token-bg-fog);
    --color-token-radio-active-foreground:               var(--color-text-foreground);

    /* link */
    --color-token-link:                                  var(--color-text-accent);
    --color-token-text-link-foreground:                  var(--color-text-accent);
    --color-token-text-link-active-foreground:           var(--color-text-accent);

    /* border */
    --color-token-border:                                var(--color-border);
    --color-token-border-default:                        var(--color-border);
    --color-token-border-heavy:                          var(--color-border-heavy);
    --color-token-border-light:                          var(--color-border-light);
    --color-token-focus-border:                          var(--color-border-focus);
    --color-token-list-focus-outline:                    var(--color-border-focus);

    /* button */
    --color-token-button-background:                     var(--color-background-button-primary);
    --color-token-button-foreground:                     var(--color-background-button-primary);
    --color-token-button-border:                         var(--color-border);
    --color-token-button-secondary-hover-background:     var(--color-background-button-secondary-hover);

    /* list / hover */
    --color-token-list-hover-background:                 var(--color-background-button-tertiary-hover);
    --color-token-toolbar-hover-background:              var(--color-background-button-tertiary-hover);
    --color-token-list-active-selection-background:      var(--color-background-button-secondary);
    --color-token-list-active-selection-foreground:      var(--color-text-foreground);
    --color-token-list-active-selection-icon-foreground: var(--color-icon-primary);

    /* badge */
    --color-token-badge-background:                      var(--color-background-button-secondary);
    --color-token-badge-foreground:                      var(--color-text-foreground-secondary);

    /* code block */
    --color-token-text-code-block-background:            var(--color-border);

    /* scrollbar */
    --color-token-scrollbar-slider-background:           var(--color-border);
    --color-token-scrollbar-slider-hover-background:     var(--color-border-heavy);
    --color-token-scrollbar-slider-active-background:    var(--color-border-heavy);

    /* editor */
    --color-token-editor-foreground:                     var(--color-text-foreground);
    --color-token-editor-background:                     var(--color-background-editor-opaque);
    --color-token-editor-error-foreground:               #ff6764;
    --color-token-editor-warning-foreground:             #ff8549;

    /* terminal */
    --color-token-terminal-foreground:                   var(--color-text-foreground);
    --color-token-terminal-background:                   var(--color-background-surface);
    --color-token-terminal-border:                       var(--color-border);
    --color-token-terminal-ansi-black:                   var(--color-text-foreground-tertiary);
    --color-token-terminal-ansi-bright-black:            var(--color-text-foreground-secondary);
    --color-token-terminal-ansi-blue:                    var(--color-accent-blue);
    --color-token-terminal-ansi-bright-blue:             var(--color-accent-blue);
    --color-token-terminal-ansi-cyan:                    var(--color-accent-blue);
    --color-token-terminal-ansi-bright-cyan:             var(--color-accent-blue);
    --color-token-terminal-ansi-green:                   var(--color-decoration-added);
    --color-token-terminal-ansi-bright-green:            var(--color-decoration-added);
    --color-token-terminal-ansi-magenta:                 var(--color-accent-purple);
    --color-token-terminal-ansi-bright-magenta:          var(--color-accent-purple);
    --color-token-terminal-ansi-red:                     #ff6764;
    --color-token-terminal-ansi-bright-red:              #ff6764;
    --color-token-terminal-ansi-white:                   var(--color-text-foreground);
    --color-token-terminal-ansi-bright-white:            var(--color-text-foreground);
    --color-token-terminal-ansi-yellow:                  #ffd240;
    --color-token-terminal-ansi-bright-yellow:           #ffd240;

    /* charts */
    --color-token-charts-blue:                           var(--color-accent-blue);
    --color-token-charts-green:                          var(--color-decoration-added);
    --color-token-charts-orange:                         #fb6a22;
    --color-token-charts-purple:                         var(--color-accent-purple);
    --color-token-charts-red:                            #ff6764;
    --color-token-charts-yellow:                         #ffd240;

    /* git decoration */
    --color-token-git-decoration-added-resource-foreground:   var(--color-decoration-added);
    --color-token-git-decoration-deleted-resource-foreground: var(--color-decoration-deleted);

    /* diff surface (mix toward foreground for contrast) */
    --color-token-diff-surface:                          color-mix(in srgb, var(--color-background-surface) 94%, var(--color-text-foreground));

    /* error / warning / status */
    --color-token-error-foreground:                      #ff6764;
    --color-icon-warning:                                #ff8549;
    --color-background-status-error:                     #4d100e;
    --color-background-status-warning:                   #4a2206;
    --color-background-status-success:                   color-mix(in oklab, #04b84c 16%, transparent);
}

/* Light-mode tweaks for status/error tokens whose dark default doesn't read on a light surface */
html.electron-light {
    --color-token-editor-error-foreground:   #b6161c;
    --color-token-editor-warning-foreground: #b55a16;
    --color-token-error-foreground:          #b6161c;
    --color-token-terminal-ansi-red:         #b6161c;
    --color-token-terminal-ansi-bright-red:  #b6161c;
    --color-token-charts-red:                #b6161c;
    --color-token-charts-orange:             #b04300;
    --color-token-charts-yellow:             #ad7e00;
    --color-icon-warning:                    #b55a16;
    --color-background-status-error:         color-mix(in oklab, #b6161c 12%, transparent);
    --color-background-status-warning:       color-mix(in oklab, #b55a16 12%, transparent);
    --color-background-status-success:       color-mix(in oklab, #04b84c 12%, transparent);
}

Visual Direction

Codex is a dense desktop tool UI. It uses a transparent macOS sidebar, a dark rounded main surface, compact 28-30px controls, low-contrast token borders, and almost no decorative gradients. The design language is practical and quiet:

Surfaces are flat or slightly elevated.
Borders are usually translucent white at very low opacity.
Hover states use subtle translucent fills.
Gradients are functional, mostly for resize affordances and fade masks.
Text is small: 12px for sidebar/control labels, 13px for body and menus.

Token Vocabulary

Codex uses Tailwind-like utility classes backed by semantic tokens. The important observed class families are:

Family	Examples	Meaning
Text	`text-token-foreground`, `text-token-description-foreground`, `text-token-muted-foreground`, `text-token-text-link-foreground`	Primary, secondary, muted, and link text
Background	`bg-token-bg-fog`, `bg-token-input-background/90`, `bg-token-side-bar-background`, `bg-token-dropdown-background`	Quiet control, composer, sidebar, dropdown surfaces
Border	`border-token-border`, `border-token-border/70`, `bg-token-border-default`	Default borders and dividers
Hover	`hover:bg-token-list-hover-background`, `enabled:hover:bg-token-list-hover-background`	Row/control hover fill
Radius	`rounded-lg`, `rounded-md`, `rounded-full`, `rounded-3xl`, `rounded-s-2xl`	Rows, icon buttons, pills, composer, main surface
Sizing	`h-toolbar`, `h-token-button-composer`, `h-token-button-composer-sm`, `size-token-button-composer`	Header and compact button heights
Spacing	`px-row-x`, `py-row-y`, `px-toolbar`, `px-panel`	System row/header/panel spacing

Computed dark colors from the inspected UI:

Use	Value
Body translucent window background	`color(srgb 0.156863 0.156863 0.156863 / 0.55)`
Main surface	`rgb(24, 24, 24)`
Primary foreground	`rgb(255, 255, 255)`
Tertiary/muted foreground	`rgba(255, 255, 255, 0.498)`
Link/accent text	`rgb(131, 195, 255)`
Button fog background	`rgba(255, 255, 255, 0.03)`
Standard border on split buttons	`rgba(255, 255, 255, 0.082)`
Main surface outline ring	`rgba(255, 255, 255, 0.157)`
Main surface shadow	`rgba(0, 0, 0, 0.08) 0px 2px 4px -1px`

Typography

Observed text sizes:

Context	Size	Line height	Weight
Body/default browser base	`16px`	`24px`	`400`
App body text / editor	`13px`	`19.5px`	`400`
Sidebar rows	`12px`	`17.1429px`	`400`
Composer footer labels	`12px`	`18px`	`400`
Header split buttons	`13px`	`18px`	`400`
Home headline	class `heading-xl`	not measured in this pass	`400` via `font-normal`

Use truncate, min-w-0, and whitespace-nowrap heavily. Codex prefers one-line labels with ellipsis over wrapping in navigation and controls.

App Shell

Window Background

The body is translucent:

background-color: color(srgb 0.156863 0.156863 0.156863 / 0.55);

The sidebar sits on this transparent window background rather than a solid panel.

Sidebar

Measured sidebar:

Width: 318.93px (319px target).
Height: full viewport.
Top padding: 46px, matching toolbar height.
Background: transparent.
Border: no visible solid sidebar border in the sampled aside itself.
Nav content begins at y = 46px.

Sidebar nav rows:

Row width: 302.93px.
Row height: 29.5px.
Row padding: 5px 8px.
Row gap: 8px.
Row radius: 12.5px.
Text size: 12px.
Line height: 17.1429px.
Hover class: hover:bg-token-list-hover-background.
Focus: focus-visible:outline-token-border, outline-2, outline-offset-2.

Section headers such as Projects are quieter:

Height: 23.5px.
Padding: 2px 4px 2px 0.
Radius: 10px.
Text size: 13px.
Color: rgba(255, 255, 255, 0.498).

Main Surface

The main work surface is the strongest framed shape:

Left offset: starts after 319px sidebar.
Background: rgb(24, 24, 24).
Radius: 12.5px 0 0 12.5px (rounded-s-2xl).
Shadow stack:

box-shadow:
  rgba(0, 0, 0, 0) 0px 0px 0px 0px,
  rgba(0, 0, 0, 0) 0px 0px 0px 0px,
  rgba(0, 0, 0, 0) 0px 0px 0px 0px,
  rgba(255, 255, 255, 0.157) 0px 0px 0px 0.5px,
  rgba(0, 0, 0, 0.08) 0px 2px 4px -1px;

The important detail is the 0.5px translucent white ring. This is the primary border for the main surface.

Borders

Borders are tokenized and low contrast. They are used more as surface separators than visible outlines.

Default Border

Split buttons and framed header controls use:

border-color: rgba(255, 255, 255, 0.082);

Observed on header split buttons:

border-token-border
border
border-r-0 or border-l-0 for attached split-button halves.

Transparent Border Reservation

Many buttons use border-transparent while still carrying the border class. This reserves layout space so hover/open states do not shift the control.

Observed examples:

Sidebar/top icon buttons.
Composer icon buttons.
Tertiary toolbar buttons.

Divider Border

Codex uses border-token-border/70 and divide-token-border/70 for quieter separators in menus/lists. The intent is visible separation only at close range.

Focus Border

Focus rings are outlines, not heavier borders:

focus-visible:outline
focus-visible:outline-2
focus-visible:outline-offset-2
focus-visible:outline-token-border

Composer send focus uses focus-visible:outline-token-button-background.

Gradients And Fades

Codex uses very few gradients. They are utility/affordance gradients, not decorative backgrounds.

Sidebar Resize Handle

The clearest actual gradient is the sidebar resize handle:

sidebar-resize-handle-line
bg-gradient-to-b
from-transparent
via-token-foreground/25
to-transparent

Measured handle:

Width: 1px.
Height: 923px in the sampled viewport.
Horizontal margin: 0 5.5px.
Initial opacity: 0.
Visible on group hover/active via group-hover:opacity-100 and group-active:opacity-100.

This gradient is a vertical line that fades at both ends.

Text Fade Masks

Long sidebar/folder rows use mask gradients when hover/focus actions appear:

group-focus-within:[mask-image:linear-gradient(to_right,transparent_0,transparent_21px,black_26px)]
group-hover:[mask-image:linear-gradient(to_right,transparent_0,transparent_21px,black_26px)]

This is not a visible background gradient. It is a text/content mask that prevents overlap with row actions.

Scroll Fade Mask

The sidebar contains vertical-scroll-fade-mask, indicating a vertical fade at scroll boundaries. Treat this as a functional overflow affordance.

Not Used As Decoration

No large hero gradients, orb gradients, or decorative color washes were observed. The main app depends on surface color, blur, borders, and shadows instead.

Header controls are compact, often split-button pairs.

Observed split button values:

Height: 28px.
Text size: 13px.
Line height: 18px.
Background: rgba(255, 255, 255, 0.03) (bg-token-bg-fog).
Border: rgba(255, 255, 255, 0.082).
Left half radius: 12.5px 0 0 12.5px.
Right half radius: 0 12.5px 12.5px 0.
Left half padding: 0 4px 0 8px.
Right half padding: 0 6px 0 2px.
Icon-only tertiary buttons: 36px x 28px, padding 0 8px, radius 12.5px, transparent border/background.

Attached split buttons remove the shared border:

Left half: border-r-0.
Right half: border-l-0.

Composer

The Codex composer is a centered, elevated input with a pill-like rounded shape.

Observed classes:

rounded-3xl
bg-token-input-background/90
ring
ring-black/10
backdrop-blur-lg
electron:shadow-[0_4px_16px_0_rgba(0,0,0,0.05)]
electron:dark:bg-token-dropdown-background

Measured composer/editor area:

Composer content width: 728px.
Editor visual width: 704px.
Editor height in empty state: 40px.
Editor max height: 25dvh.
ProseMirror min height: 2rem.
Text size: 13px.
Line height: 19.5px.

Composer footer:

Width: 728px.
Height: 28px.
Display: grid.
Columns: minmax(0, auto) auto minmax(0, 1fr).
Gap: 5px.
Padding: 0 8px.
Margin bottom: 8px.

Footer controls:

Main button height: 28px.
Small button height: 28px in measured state.
Label font: 12px.
Label line height: 18px.
Pill radius: 9999px.
Text color for inactive controls: rgba(255, 255, 255, 0.498).
Link/accent label color: rgb(131, 195, 255).
Icon-only composer buttons: 28px x 28px.
Send button: 28px x 28px, 9999px radius, white background, 0.5 opacity when disabled.

Buttons

General button pattern:

Keep a border even when transparent.
Use cursor-interaction.
Use user-select-none.
Use whitespace-nowrap.
Disabled state: disabled:cursor-not-allowed and either disabled:opacity-40 or disabled:opacity-50.
Hover/open state: enabled:hover:bg-token-list-hover-background and data-[state=open]:bg-token-list-hover-background.

Control sizes:

Control	Size
Sidebar row	`303px x 30px` sampled
Header split button	`28px` high
Header icon-only tertiary	`36px x 28px`
Sidebar section icon button	`24px x 24px`
Composer icon button	`28px x 28px`
Composer send button	`28px x 28px`

Radius Scale

Observed radii:

Radius	Use
`10px`	Section toggle, compact icon button
`12.5px`	Sidebar rows, header split buttons, main surface side radius
`9999px`	Composer footer pills and circular send button
`rounded-3xl`	Composer shell
`rounded-b-2xl`	Lower rounded panel in prompt/options area

Codex often uses rounded-lg utility classes, but computed radius in the sampled environment is 12.5px.

Spacing Scale

Observed spacing:

Context	Value
Sidebar row padding	`5px 8px`
Sidebar row gap	`8px`
Section toggle padding	`2px 4px 2px 0`
Header split left padding	`0 4px 0 8px`
Header split right padding	`0 6px 0 2px`
Header icon padding	`0 8px`
Composer footer padding	`0 8px`
Composer footer gap	`5px`
Composer footer bottom margin	`8px`
Composer small pill padding	`0 6px`
Composer standard pill padding	`0 8px`

Shadows And Elevation

Codex uses minimal elevation:

Main surface: 0.5px white ring plus subtle shadow.
Composer: 0 4px 16px rgba(0,0,0,0.05) in Electron.
Dropdown/composer background uses blur and opaque token surfaces rather than large shadows.

The main visual separation comes from border rings and surface contrast, not heavy drop shadows.

Plugins Catalog

The Plugins screen keeps the same shell but uses content-centered catalog sections.

Observed structure:

Main content still begins at x = 319px and uses the same main-surface.
Header height remains 46px.
Content column is centered with max-width around 736px.
Catalog sections use transparent backgrounds and gap-4.
Section examples:
- Featured/plugin rows: x = 463, width = 736.
- Vertical section gaps are large enough that categories read as separate bands without card wrappers.

Header tabs/actions on the Plugins page:

Header text includes Plugins, Skills, Manage, Create.
These are compact header controls rather than large tabs.
They inherit the same 28px control language as toolbar buttons.

Plugin detail rows/cards:

Plugin settings pages use bordered list cards rather than heavy panels.
Example Computer Use plugin row:
- Rect: 672px x 62px.
- Radius: 12.5px.
- Border: 1px rgba(255, 255, 255, 0.082).
- Class pattern: border-token-border/40 flex flex-col gap-2.5 rounded-2xl border p-2.5 transition.
Action button such as Try in Chat:
- Size: 28px x 28px.
- Radius: 10px.
- Transparent background and transparent reserved border.

Automations

The Automations screen introduces rounded prompt/template cards.

Page layout:

Header action: New automation, white filled button.
Content header column: x = 447, width = 768, with px-panel.
Template section width: 728px.
Template sections use flex flex-col gap-4.

Automation template cards:

Card width: 356px.
Card height: usually 97px; shorter cards can be 78px.
Two-column grid inside the 728px content column.
Background: oklab(0.297161 0.0000135154 0.00000594556 / 0.672549).
Border: 1px oklab(0.999994 0.0000455678 0.0000200868 / 0.0411765).
Radius: 30px (rounded-4xl).
Padding class: px-3 py-3.
Text size: 13px, line-height 19.5px.
Hover classes strengthen the card: hover:border-token-border and hover:bg-token-input-background.

This is the largest radius observed in normal content cards. It is used for selectable prompt templates, not ordinary panels.

Clicking the sidebar Settings row first opens an account popover near the lower-left sidebar.

Measured popover:

Rect: x = 8, y = 663, width = 282, height = 176.
It contains account identity, account type, settings, rate limits, and log out.
The popover itself is visually transparent in computed background, relying on internal menu structure and separators.
Separators:
- Width: 256px.
- Height: 1px.
- Background: rgba(255, 255, 255, 0.082).
- Class: bg-token-menu-border.

This popover confirms menu separators use the same low-contrast border color as split-button borders.

Settings Shell

The actual Settings surface is a separate app state with a fixed left settings nav and a right content panel.

Settings nav:

Nav width: 300px.
Nav starts below toolbar at y = 46px.
Nav padding class: px-row-x.
Row width: 284px.
Row height: 30px.
Row padding uses the same px-row-x py-row-y token pair as main sidebar rows.
Row radius: 12.5px.
Row text: 12px, line-height 17.1429px.
Active background: rgba(255, 255, 255, 0.08).
Items observed:
- General
- Appearance
- Configuration
- Personalization
- MCP servers
- Git
- Environments
- Worktrees
- Browser use
- Computer use
- Archived chats
- Usage

Settings content:

Content starts at x = 300px.
Top header strip: height = 46px.
Scroll panel: x = 300, y = 46, width = 1044, height = 831.
Content class: flex-1 overflow-y-auto p-panel.
Inner content column:
- Usually x = 486.
- Width: 672px.
- Header block height: 67px.
- Section group gap: var(--padding-panel).

Settings headings are plain text blocks, not cards. Most settings sections are transparent rows and sections; controls provide the visual weight.

Settings: General

General contains work-mode cards, switches, dropdown buttons, and segmented controls.

Work mode cards:

Two side-by-side cards.
Each card: 330px x 284px.
Radius: 12.5px.
Selected background: rgba(255, 255, 255, 0.08).
Unselected background: rgb(24, 24, 24).
Unselected border: 1px rgba(255, 255, 255, 0.082).
Class pattern: cursor-interaction flex min-h-[284px] w-full min-w-0 flex-col items-center.

Switches:

Switch button size: 32px x 20px.
Text around switches uses 12px.
Switch buttons report transparent background at the outer button level; the visual track/thumb is inside child elements.
Focus class: focus-visible:ring-2.
Aria labels carry the setting names, for example:
- Default permissions are always shown
- Show Auto-review in the composer
- Show Full access in the composer
- Prevent sleep while running
- Enable ambient suggestions
- Enable permission notifications
- Enable question notifications

Dropdown/select-like buttons:

Width: often 240px.
Height: 28px.
Radius: 12.5px.
Background: oklab(0.999994 0.0000455678 0.0000200868 / 0.05).
Border is reserved but transparent: 1px rgba(0, 0, 0, 0).
Text size: 13px, line-height 18px.
Examples: VS Code, Auto Detect, Standard, Only when unfocused.

Small action buttons:

Set buttons are 38px x 28px.
Same radius/background/font as dropdown buttons.

Segmented pills:

Height: 24px.
Radius: 9999px.
Text size: 12px, line-height 18px.
Selected background: oklab(0.999994 0.0000455678 0.0000200868 / 0.05).
Unselected background: transparent.
Examples: Queue / Steer, Inline / Detached.

Settings: Appearance

Appearance adds theme segmented controls, theme import/copy actions, code theme select, swatches, and sliders.

Theme segmented control:

Buttons: Light, Dark, System.
Height: 24px.
Radius: 9999px.
Text size: 12px, line-height 18px.
Selected Dark background: oklab(0.999994 0.0000455678 0.0000200868 / 0.05).
Unselected buttons are transparent.

Theme actions:

Import: 58px x 28px.
Copy theme: 91px x 28px.
Radius: 12.5px.
Transparent background and transparent reserved border.
Text size: 13px, line-height 18px.

Code theme selector:

Example: Aa Codex.
Size: 240px x 28px.
Background: oklab(0.999994 0.0000455678 0.0000200868 / 0.05).
Radius: 12.5px.
Box shadow includes a tiny 0 1px 2px -1px rgba(0,0,0,0.08).

Color swatches:

Small swatch buttons measured at 14px x 14px.
Background color carries the swatch value, for example accent green/blue.
Swatches are much smaller than toolbar buttons and are embedded in rows.

Settings: Plugin Panels

Browser Use and Computer Use settings use the same plugin panel pattern:

Header block: transparent, 672px wide.
Section groups are transparent and stacked with var(--padding-panel).
Plugin summary cards use:
- border-token-border/40
- rounded-2xl
- border
- p-2.5
- gap-2.5
- transition
Try/action icon button:
- 28px x 28px.
- Radius: 10px.
- Transparent background and transparent reserved border.

This is a quieter, smaller card style than Automation templates.

Settings: Archived Chats

Archived chats is a list surface:

Content column: 672px.
List section uses flex flex-col gap-2.
Rows are transparent sections rather than cards.
Row actions use standard 28px buttons.
Unarchive button:
- Size: 79px x 28px.
- Background: oklab(0.999994 0.0000455678 0.0000200868 / 0.05).
- Radius: 12.5px.
- Text size: 13px, line-height 18px.
- Transparent reserved border.

Settings: Usage

Usage uses transparent sections with progress/limit content and standard actions.

Observed sections:

General usage limits
GPT-5.3-Codex-Spark usage limits
Credit

Section layout:

Section width: 672px.
Usage limit sections measured 672px x 173px.
Credit section measured 672px x 189px.
Sections are transparent; progress values and row text provide structure.

Actions:

Purchase: 74px x 28px.
Settings: 68px x 28px.
Background: oklab(0.999994 0.0000455678 0.0000200868 / 0.05).
Radius: 12.5px.
Text size: 13px, line-height 18px.

Links:

Links can use muted secondary text rather than blue when they are ancillary.
Example Doc: text-token-text-secondary hover:text-token-text-primary.

Practical Replication Rules

Use semantic tokens/classes first: foreground, description foreground, border, list hover, fog, input background.
Keep controls compact: 28px for toolbar/composer controls, 30px for nav rows.
Reserve border space with transparent borders to avoid hover layout shift.
Use 12.5px radii for rows and split controls; use full pill radius for composer footer controls.
Use gradients only for resize handles, overflow fades, or masks.
Use 0.5px translucent rings for major surfaces instead of strong 1px borders.
Keep text at 12px or 13px for operational UI.
Use min-w-0, truncate, and mask fades anywhere row actions can overlap labels.
Use 30px radius only for large selectable prompt/template cards.
In settings, keep the content column at about 672px and let controls carry the visual framing.

56 KiB Raw Permalink Blame History Unescape Escape

Codex Design System Notes

Theming Pipeline (reverse-engineered)

Inputs (per theme — Light, Dark)

Resolution flow

The shaping function

Token derivation buckets

Empirical token table (light theme, ink=#0d0d0d, surface=#ffffff, accent=#0169cc)

Effects of changing each input

Design ideas

Token Counts

Built-in Themes Catalog

Kind 1 — first-class chrome themes (12 files)

Kind 2 — VS Code code themes (~55 files)

Catalog (Codium ships)

Limitations of synthesis

JS Derivation Functions

Inputs

Color helpers

Shaping function

Per-token coefficient table

Main derivation

Apply to the document

CSS-Side Aliases

Visual Direction

Token Vocabulary

Typography

App Shell

Window Background

Sidebar

Main Surface

Borders

Default Border

Transparent Border Reservation

Divider Border

Focus Border

Gradients And Fades

Sidebar Resize Handle

Text Fade Masks

Scroll Fade Mask

Not Used As Decoration

Toolbar And Header Controls

Composer

Buttons

Radius Scale

Spacing Scale

Shadows And Elevation

Plugins Catalog

Automations

Account Popover

Settings Shell

Settings: General

Settings: Appearance

Settings: Plugin Panels

Settings: Archived Chats

Settings: Usage

Practical Replication Rules

56 KiB

Raw Permalink Blame History

Inputs (per theme — `Light`, `Dark`)

Empirical token table (light theme, `ink=#0d0d0d`, `surface=#ffffff`, `accent=#0169cc`)