Mono Slate

# DESIGN.md — Mono Slate

> Design context for AI coding agents. Paste this file into Cursor, Claude Code, Codex, v0 or Lovable
> before asking for UI, or commit it at your repo root as `DESIGN.md`.

- **Source:** [Mono Slate on CSS Crème](https://csscreme.com/themes/mono-slate)
- **Default mode:** light
- **Tags:** mono, minimal, professional
- **Install as a real shadcn/ui theme:** `npx shadcn@latest add https://csscreme.com/r/mono-slate.json`
- **Fingerprint:** `fnv1a-9b4e7c34` — a hash of the token set below. It changes only when a token changes.
- **Verify this copy:** call the MCP tool `verify_design_md` with `{ "id": "mono-slate", "fingerprint": "fnv1a-9b4e7c34" }`
  at `https://csscreme.com/mcp`, or refetch https://csscreme.com/d/mono-slate.md. A stale copy is worse than none: an agent will follow it faithfully.
- **Also available as:** [DTCG tokens](https://csscreme.com/d/mono-slate.tokens.json) for Tokens Studio / Figma Variables · [agent rules block](https://csscreme.com/d/mono-slate.rules.md) for CLAUDE.md, AGENTS.md or .cursor/rules

A grayscale system with one cool-blue accent — the safest choice for content-heavy, no-nonsense interfaces.

---

## Semantic color roles

Six roles carry the identity. Everything else in this file is derived from them.

| Role | Hex | OKLCH | Use it for |
| --- | --- | --- | --- |
| `bg` | `#F8FAFC` | `oklch(98.4% 0.003 247.9)` | page background |
| `surface` | `#FFFFFF` | `oklch(100.0% 0.000 89.9)` | cards, panels, popovers |
| `primary` | `#334155` | `oklch(37.2% 0.039 257.3)` | brand actions: primary buttons, links, focus rings |
| `accent` | `#2563EB` | `oklch(54.6% 0.215 262.9)` | secondary emphasis only, never a second primary |
| `text` | `#0F172A` | `oklch(20.8% 0.040 265.8)` | body and heading text |
| `muted` | `#64748B` | `oklch(55.4% 0.041 257.4)` | secondary text, borders, disabled states |

## Full token set (shadcn/ui, both modes)

Colors are OKLCH (Tailwind v4 / shadcn native). Brand colors are identical in both modes by design:
only the neutrals move, and they keep their hue, so light and dark read as the same design system.

| Token | Light | Dark |
| --- | --- | --- |
| `--background` | `oklch(98.4% 0.003 247.9)` | `oklch(18.5% 0.008 248.2)` |
| `--foreground` | `oklch(20.8% 0.040 265.8)` | `oklch(96.4% 0.003 264.5)` |
| `--card` | `oklch(100.0% 0.000 89.9)` | `oklch(25.2% 0.000 89.9)` |
| `--card-foreground` | `oklch(20.8% 0.040 265.8)` | `oklch(96.4% 0.003 264.5)` |
| `--popover` | `oklch(100.0% 0.000 89.9)` | `oklch(25.2% 0.000 89.9)` |
| `--popover-foreground` | `oklch(20.8% 0.040 265.8)` | `oklch(96.4% 0.003 264.5)` |
| `--primary` | `oklch(37.2% 0.039 257.3)` | `oklch(37.2% 0.039 257.3)` |
| `--primary-foreground` | `oklch(100.0% 0.000 89.9)` | `oklch(100.0% 0.000 89.9)` |
| `--secondary` | `oklch(99.4% 0.001 286.4)` | `oklch(23.0% 0.002 247.9)` |
| `--secondary-foreground` | `oklch(20.8% 0.040 265.8)` | `oklch(96.4% 0.003 264.5)` |
| `--muted` | `oklch(99.4% 0.001 286.4)` | `oklch(23.0% 0.002 247.9)` |
| `--muted-foreground` | `oklch(55.4% 0.041 257.4)` | `oklch(70.5% 0.007 255.5)` |
| `--accent` | `oklch(54.6% 0.215 262.9)` | `oklch(54.6% 0.215 262.9)` |
| `--accent-foreground` | `oklch(100.0% 0.000 89.9)` | `oklch(100.0% 0.000 89.9)` |
| `--destructive` | `oklch(62.6% 0.193 23.0)` | `oklch(62.6% 0.193 23.0)` |
| `--destructive-foreground` | `oklch(15.2% 0.009 285.3)` | `oklch(15.2% 0.009 285.3)` |
| `--border` | `oklch(83.9% 0.015 254.6)` | `oklch(34.7% 0.008 255.5)` |
| `--input` | `oklch(83.9% 0.015 254.6)` | `oklch(34.7% 0.008 255.5)` |
| `--ring` | `oklch(37.2% 0.039 257.3)` | `oklch(37.2% 0.039 257.3)` |
| `--chart-1` | `oklch(37.2% 0.039 257.3)` | `oklch(37.2% 0.039 257.3)` |
| `--chart-2` | `oklch(54.6% 0.215 262.9)` | `oklch(54.6% 0.215 262.9)` |
| `--chart-3` | `oklch(34.6% 0.059 295.3)` | `oklch(34.6% 0.059 295.3)` |
| `--chart-4` | `oklch(42.3% 0.040 188.7)` | `oklch(42.3% 0.040 188.7)` |
| `--chart-5` | `oklch(45.5% 0.134 262.7)` | `oklch(45.5% 0.134 262.7)` |
| `--sidebar` | `oklch(99.4% 0.002 247.8)` | `oklch(22.0% 0.004 229.0)` |
| `--sidebar-foreground` | `oklch(20.8% 0.040 265.8)` | `oklch(96.4% 0.003 264.5)` |
| `--sidebar-primary` | `oklch(37.2% 0.039 257.3)` | `oklch(37.2% 0.039 257.3)` |
| `--sidebar-primary-foreground` | `oklch(100.0% 0.000 89.9)` | `oklch(100.0% 0.000 89.9)` |
| `--sidebar-accent` | `oklch(99.4% 0.001 286.4)` | `oklch(23.0% 0.002 247.9)` |
| `--sidebar-accent-foreground` | `oklch(20.8% 0.040 265.8)` | `oklch(96.4% 0.003 264.5)` |
| `--sidebar-border` | `oklch(83.9% 0.015 254.6)` | `oklch(34.7% 0.008 255.5)` |
| `--sidebar-ring` | `oklch(37.2% 0.039 257.3)` | `oklch(37.2% 0.039 257.3)` |

**What is measured and what is derived.** The six roles are the source. `chart-*` and `sidebar-*` follow
fixed rules over them (chart-1 = primary, chart-2 = accent, chart-3/4 = primary rotated ±40°, chart-5 = the
primary–accent midpoint; sidebar maps onto surface, border and primary). `shadow-*` is the foreground
colour at a fixed opacity per step. None of those is a measurement, and an agent should treat them as
defaults it may override, unlike the six roles, which it may not.

## Typography

- **Headings:** Inter
- **Body:** Inter

## Shape and rhythm

- **Radius:** `8px` (the `--radius` token; derive smaller/larger from it, do not invent new values)
- **Spacing scale:** 4px base · 4 / 8 / 12 / 16 / 24 / 32 / 48

## Contrast, measured

Computed from the tokens above in light mode, not asserted. Ratios are WCAG 2.1 relative luminance.

| Pair | Foreground | Background | Ratio | Verdict |
| --- | --- | --- | --- | --- |
| Body text on page background | `#0F172A` | `#F8FAFC` | 17.06:1 | AAA |
| Body text on card | `#0F172A` | `#FFFFFF` | 17.85:1 | AAA |
| Muted text on page background | `#64748B` | `#F8FAFC` | 4.55:1 | AA |
| Button label on primary | `#ffffff` | `#334155` | 10.35:1 | AAA |
| Button label on accent | `#ffffff` | `#2563EB` | 5.17:1 | AA |

## Rules for the agent

These are constraints, not suggestions. Each one is checkable against the tables above.

1. **Use only the tokens listed here.** Do not introduce a hex value that is not in the token table. If
   you need an in-between shade, mix two existing tokens rather than inventing a new hue.
2. **`#334155` (primary) is the only call-to-action color.** One primary action per view. `accent`
   is for secondary emphasis and must never be styled as a second primary button.
3. **Never restyle brand colors between light and dark.** Only neutrals change mode. A theme whose
   primary shifts between modes is a different theme.
4. **Respect the radius token.** Every corner derives from `8px`. Mixed radii across a view is
   the most common tell of generated UI.
5. **Stay on the spacing scale.** 4px base · 4 / 8 / 12 / 16 / 24 / 32 / 48. No arbitrary pixel values.
6. **Do not drop below the contrast ratios above.** If a combination you need is not in the contrast
   table, compute it before shipping it. Text under 4.5:1 fails AA.
7. **Headings in Inter, body in Inter.** Do not add a third family.
8. **Use the semantic role, not the raw color.** Write `var(--primary)`, never `#334155`, so the
   theme stays swappable.

## CSS variables

Paste into `globals.css`:

```css
:root {
  --background: oklch(98.4% 0.003 247.9);
  --foreground: oklch(20.8% 0.040 265.8);
  --card: oklch(100.0% 0.000 89.9);
  --card-foreground: oklch(20.8% 0.040 265.8);
  --popover: oklch(100.0% 0.000 89.9);
  --popover-foreground: oklch(20.8% 0.040 265.8);
  --primary: oklch(37.2% 0.039 257.3);
  --primary-foreground: oklch(100.0% 0.000 89.9);
  --secondary: oklch(99.4% 0.001 286.4);
  --secondary-foreground: oklch(20.8% 0.040 265.8);
  --muted: oklch(99.4% 0.001 286.4);
  --muted-foreground: oklch(55.4% 0.041 257.4);
  --accent: oklch(54.6% 0.215 262.9);
  --accent-foreground: oklch(100.0% 0.000 89.9);
  --destructive: oklch(62.6% 0.193 23.0);
  --destructive-foreground: oklch(15.2% 0.009 285.3);
  --border: oklch(83.9% 0.015 254.6);
  --input: oklch(83.9% 0.015 254.6);
  --ring: oklch(37.2% 0.039 257.3);
  --chart-1: oklch(37.2% 0.039 257.3);
  --chart-2: oklch(54.6% 0.215 262.9);
  --chart-3: oklch(34.6% 0.059 295.3);
  --chart-4: oklch(42.3% 0.040 188.7);
  --chart-5: oklch(45.5% 0.134 262.7);
  --sidebar: oklch(99.4% 0.002 247.8);
  --sidebar-foreground: oklch(20.8% 0.040 265.8);
  --sidebar-primary: oklch(37.2% 0.039 257.3);
  --sidebar-primary-foreground: oklch(100.0% 0.000 89.9);
  --sidebar-accent: oklch(99.4% 0.001 286.4);
  --sidebar-accent-foreground: oklch(20.8% 0.040 265.8);
  --sidebar-border: oklch(83.9% 0.015 254.6);
  --sidebar-ring: oklch(37.2% 0.039 257.3);
  --radius: 8px;
  --shadow-2xs: 0 1px 2px 0px rgb(15 23 42 / 0.05);
  --shadow-xs: 0 1px 3px 0px rgb(15 23 42 / 0.06);
  --shadow-sm: 0 1px 3px 0px rgb(15 23 42 / 0.08), 0 1px 2px -1px rgb(15 23 42 / 0.08);
  --shadow-md: 0 4px 6px -1px rgb(15 23 42 / 0.09), 0 2px 4px -2px rgb(15 23 42 / 0.09);
  --shadow-lg: 0 10px 15px -3px rgb(15 23 42 / 0.1), 0 4px 6px -4px rgb(15 23 42 / 0.1);
  --shadow-xl: 0 20px 25px -5px rgb(15 23 42 / 0.12), 0 8px 10px -6px rgb(15 23 42 / 0.12);
  --shadow-2xl: 0 25px 50px -12px rgb(15 23 42 / 0.22);
  --spacing: 4px;
}

.dark {
  --background: oklch(18.5% 0.008 248.2);
  --foreground: oklch(96.4% 0.003 264.5);
  --card: oklch(25.2% 0.000 89.9);
  --card-foreground: oklch(96.4% 0.003 264.5);
  --popover: oklch(25.2% 0.000 89.9);
  --popover-foreground: oklch(96.4% 0.003 264.5);
  --primary: oklch(37.2% 0.039 257.3);
  --primary-foreground: oklch(100.0% 0.000 89.9);
  --secondary: oklch(23.0% 0.002 247.9);
  --secondary-foreground: oklch(96.4% 0.003 264.5);
  --muted: oklch(23.0% 0.002 247.9);
  --muted-foreground: oklch(70.5% 0.007 255.5);
  --accent: oklch(54.6% 0.215 262.9);
  --accent-foreground: oklch(100.0% 0.000 89.9);
  --destructive: oklch(62.6% 0.193 23.0);
  --destructive-foreground: oklch(15.2% 0.009 285.3);
  --border: oklch(34.7% 0.008 255.5);
  --input: oklch(34.7% 0.008 255.5);
  --ring: oklch(37.2% 0.039 257.3);
  --chart-1: oklch(37.2% 0.039 257.3);
  --chart-2: oklch(54.6% 0.215 262.9);
  --chart-3: oklch(34.6% 0.059 295.3);
  --chart-4: oklch(42.3% 0.040 188.7);
  --chart-5: oklch(45.5% 0.134 262.7);
  --sidebar: oklch(22.0% 0.004 229.0);
  --sidebar-foreground: oklch(96.4% 0.003 264.5);
  --sidebar-primary: oklch(37.2% 0.039 257.3);
  --sidebar-primary-foreground: oklch(100.0% 0.000 89.9);
  --sidebar-accent: oklch(23.0% 0.002 247.9);
  --sidebar-accent-foreground: oklch(96.4% 0.003 264.5);
  --sidebar-border: oklch(34.7% 0.008 255.5);
  --sidebar-ring: oklch(37.2% 0.039 257.3);
  --shadow-2xs: 0 1px 2px 0px rgb(242 243 245 / 0.16);
  --shadow-xs: 0 1px 3px 0px rgb(242 243 245 / 0.18);
  --shadow-sm: 0 1px 3px 0px rgb(242 243 245 / 0.22), 0 1px 2px -1px rgb(242 243 245 / 0.22);
  --shadow-md: 0 4px 6px -1px rgb(242 243 245 / 0.26), 0 2px 4px -2px rgb(242 243 245 / 0.26);
  --shadow-lg: 0 10px 15px -3px rgb(242 243 245 / 0.3), 0 4px 6px -4px rgb(242 243 245 / 0.3);
  --shadow-xl: 0 20px 25px -5px rgb(242 243 245 / 0.34), 0 8px 10px -6px rgb(242 243 245 / 0.34);
  --shadow-2xl: 0 25px 50px -12px rgb(242 243 245 / 0.45);
}
```

Tailwind v4 maps them into utilities:

```css
@theme inline {
  --color-background: var(--background);
  --color-foreground: var(--foreground);
  --color-card: var(--card);
  --color-card-foreground: var(--card-foreground);
  --color-popover: var(--popover);
  --color-popover-foreground: var(--popover-foreground);
  --color-primary: var(--primary);
  --color-primary-foreground: var(--primary-foreground);
  --color-secondary: var(--secondary);
  --color-secondary-foreground: var(--secondary-foreground);
  --color-muted: var(--muted);
  --color-muted-foreground: var(--muted-foreground);
  --color-accent: var(--accent);
  --color-accent-foreground: var(--accent-foreground);
  --color-destructive: var(--destructive);
  --color-destructive-foreground: var(--destructive-foreground);
  --color-border: var(--border);
  --color-input: var(--input);
  --color-ring: var(--ring);
  --color-chart-1: var(--chart-1);
  --color-chart-2: var(--chart-2);
  --color-chart-3: var(--chart-3);
  --color-chart-4: var(--chart-4);
  --color-chart-5: var(--chart-5);
  --color-sidebar: var(--sidebar);
  --color-sidebar-foreground: var(--sidebar-foreground);
  --color-sidebar-primary: var(--sidebar-primary);
  --color-sidebar-primary-foreground: var(--sidebar-primary-foreground);
  --color-sidebar-accent: var(--sidebar-accent);
  --color-sidebar-accent-foreground: var(--sidebar-accent-foreground);
  --color-sidebar-border: var(--sidebar-border);
  --color-sidebar-ring: var(--sidebar-ring);
  --radius: var(--radius);
  --radius-sm: calc(var(--radius) - 4px);
  --radius-md: calc(var(--radius) - 2px);
  --radius-lg: var(--radius);
  --radius-xl: calc(var(--radius) + 4px);
  --shadow-2xs: var(--shadow-2xs);
  --shadow-xs: var(--shadow-xs);
  --shadow-sm: var(--shadow-sm);
  --shadow-md: var(--shadow-md);
  --shadow-lg: var(--shadow-lg);
  --shadow-xl: var(--shadow-xl);
  --shadow-2xl: var(--shadow-2xl);
  --spacing: var(--spacing);
}
```

---

Generated by [CSS Crème](https://csscreme.com) — curated web design, decoded so you can build it.
Every value above is computed from the palette, not written by hand.