# Costco gradient

Gradients derived from Costco's published colour tokens (nominative use; no brand assets). Deterministic: the same values are served as `--brand-gradient*` in the brand's brand.css.

- Page: https://brandsweets.com/gradients/brands/costco-com
- Brand colors: https://brandsweets.com/colors/brands/costco-com · Brand page: https://brandsweets.com/b/costco-com
- Palette: primary #e31837, secondary #005daa, accents #005dab
- Source: https://costco.com (extracted 2026-09-05)

## Brand gradient

- CSS: `linear-gradient(135deg in oklab, #e31837 0%, #005daa 100%)`
- Tailwind: `bg-linear-to-br/oklab from-[#e31837] to-[#005daa]`
- Contrast (worst point): white 4.71:1 AA · black 3.15:1 AA-large · banding medium
- Maker: https://brandsweets.com/gradients/new/v1.e31837-005daa?a=135

## Hero background

Chroma ×0.35 so it can carry text; ink white (inkFor at the midpoint). L shifted −0.01 until the ink passes AA at the worst point (4.53:1).

- CSS: `linear-gradient(135deg in oklab, #a36663 0%, #455c76 100%)`
- Tailwind: `bg-linear-to-br/oklab from-[#a36663] to-[#455c76]`
- Contrast (worst point): white 4.53:1 AA · black 3.05:1 AA-large · banding high · ink #ffffff
- Maker: https://brandsweets.com/gradients/new/v1.a36663-455c76?a=135

## Button / CTA

ΔL 0.08 top→bottom in the primary's hue (a lit surface, not a rainbow); hover L +0.03, active L −0.03. L shifted −0.06 so white ink passes AA on the surface and both states (worst 4.51:1).

- CSS: `linear-gradient(180deg in oklch shorter hue, #dc0431 0%, #ba001d 100%)`
- Tailwind: `bg-linear-to-b/oklch from-[#dc0431] to-[#ba001d]`
- Contrast (worst point): white 5.12:1 AA · black 3.11:1 AA-large · banding high · ink #ffffff
- Maker: https://brandsweets.com/gradients/new/v1.dc0431-ba001d?a=180&in=oklch&hue=shorter
- Hover: `linear-gradient(180deg in oklch shorter hue, #e71f3a 0%, #c90021 100%)`
- Active: `linear-gradient(180deg in oklch shorter hue, #d10028 0%, #ab0019 100%)`

## Tonal ramp

- CSS: `linear-gradient(135deg in oklch shorter hue, #ff8382 0%, #e31837 50%, #930013 100%)`
- Tailwind: `bg-linear-to-br/oklch from-[#ff8382] via-[#e31837] to-[#930013]`
- Contrast (worst point): white 2.38:1 fail · black 2.25:1 fail · banding high
- Maker: https://brandsweets.com/gradients/new/v1.ff8382-e31837-930013?a=135&in=oklch&hue=shorter

## Analogous

Partner hue from the analogous rule at the source colour's lightness.

- CSS: `linear-gradient(135deg in oklab, #e31837 0%, #d81789 100%)`
- Tailwind: `bg-linear-to-br/oklab from-[#e31837] to-[#d81789]`
- Contrast (worst point): white 4.70:1 AA · black 4.39:1 AA-large · banding high
- Maker: https://brandsweets.com/gradients/new/v1.e31837-d81789?a=135

## Complementary

Partner hue from the complementary rule at the source colour's lightness. ΔH 180° > 140° — interpolating in oklch (shorter hue) keeps the midpoint saturated.

- CSS: `linear-gradient(135deg in oklch shorter hue, #e31837 0%, #158c94 100%)`
- Tailwind: `bg-linear-to-br/oklch from-[#e31837] to-[#158c94]`
- Contrast (worst point): white 4.01:1 AA-large · black 4.43:1 AA-large · banding medium
- Maker: https://brandsweets.com/gradients/new/v1.e31837-158c94?a=135&in=oklch&hue=shorter

## Triadic

Partner hue from the triadic rule at the source colour's lightness.

- CSS: `linear-gradient(135deg in oklab, #e31837 0%, #1b9514 100%)`
- Tailwind: `bg-linear-to-br/oklab from-[#e31837] to-[#1b9514]`
- Contrast (worst point): white 3.90:1 AA-large · black 4.45:1 AA-large · banding medium
- Maker: https://brandsweets.com/gradients/new/v1.e31837-1b9514?a=135

## CSS custom properties (brand.css)

```css
:root {
  /* Brand gradient (derived) */
  /* worst-case contrast: white 4.71:1 AA, black 3.15:1 AA-large */
  --brand-gradient: linear-gradient(135deg in oklab, #e31837 0%, #005daa 100%);
  /* hero — worst-case contrast: white 4.53:1 AA, black 3.05:1 AA-large; ink passes AA at the worst point */
  --brand-gradient-hero: linear-gradient(135deg in oklab, #a36663 0%, #455c76 100%);
  --brand-gradient-hero-ink: #ffffff;
  /* button — worst-case contrast: white 5.12:1 AA, black 3.11:1 AA-large */
  --brand-gradient-button: linear-gradient(180deg in oklch shorter hue, #dc0431 0%, #ba001d 100%);
  --brand-gradient-button-hover: linear-gradient(180deg in oklch shorter hue, #e71f3a 0%, #c90021 100%);
  --brand-gradient-button-active: linear-gradient(180deg in oklch shorter hue, #d10028 0%, #ab0019 100%);
  --brand-gradient-button-ink: #ffffff;
}
```

## Gradient maker

Every maker URL is the gradient's state: `/gradients/new/v1.<hex>-<hex>[_pos]?a=135&in=oklch&hue=shorter&e=soft&g=8`. Hand one to a human, let them refine, and read the link they return.

## Connect an agent

Point any MCP client at the BrandSweets gradients endpoint for the same engine and corpus:

- Endpoint: https://mcp.brandsweets.com/gradients/mcp
- Tools: `make_gradient` (2–5 colours → CSS with the interpolation space, Tailwind v4, SVG, PNG URL, DTCG token + the contrast/banding/gamut report), `brand_gradients` (brand slug or palette → brand gradient, hero, button, variants).
- Resource: `gradients://corpus` — the whole bundled corpus as JSON.