LangChain

# LangChain Design System — .cursorrules
# Generated by StyleExtract · styleextract.com/vault/langchain

You are a senior frontend developer building UI that matches the LangChain design system exactly.
Read this entire file before writing any component.

## Brand Identity
Company    : LangChain
Primary    : #4ADE80
Secondary  : #1C3C3C
Accent     : #FFFFFF
Font       : Inter, system-ui
Radius     : 6px
Voice      : Dark with green accents — the developer framework for LLM applications.

## CSS Custom Properties
```css
:root {
  --color-primary:   #4ADE80;
  --color-secondary: #1C3C3C;
  --color-accent:    #FFFFFF;
  --color-text:      #FFFFFF;
  --color-surface:   #1C1C1E;
  --color-border:    #2C2C2E;
  --font-sans:       "Inter", system-ui, -apple-system, sans-serif;
  --radius:          6px;
}
```

## Tailwind Config
```js
// tailwind.config.js
module.exports = {
  theme: {
    extend: {
      colors: {
        primary:   "#4ADE80",
        secondary: "#1C3C3C",
        accent:    "#FFFFFF",
      },
      fontFamily: {
        sans: ["Inter", "system-ui", "sans-serif"],
      },
      borderRadius: {
        brand: "6px",
      },
    },
  },
};
```

## Typography
```
heading-font:    Inter, system-ui
heading-weight:  700
heading-tracking: -0.02em
body-font:       Inter, system-ui
body-size:       16px
body-line-height: 1.6
```

## Spacing Scale
Base: 4px  |  Scale: 4 · 8 · 12 · 16 · 24 · 32 · 48 · 64 · 96px
Never use arbitrary values like 13px, 22px, or 50px.

## Component Rules

### Primary Button
background-color: #4ADE80
color: #1D1D1F
border-radius: 6px
padding: 12px 24px
font-weight: 600
font-size: 14px
transition: opacity 0.15s
&:hover { opacity: 0.88 }

### Secondary Button
background-color: transparent
border: 1.5px solid #4ADE80
color: #4ADE80
border-radius: 6px
padding: 11px 23px

### Card
background: #1C1C1E
border: 1px solid #2C2C2E
border-radius: 16px
padding: 24px
box-shadow: 0 1px 3px rgba(0,0,0,0.08)

### Navigation
background: #1C3C3C
color: #FFFFFF
height: 60px
padding: 0 24px
```

## Rules
DO:
- Use the exact hex values defined in CSS Custom Properties
- Maintain LangChain's aesthetic: Dark with green accents — the developer framework for LLM applications.
- Apply 4px base-unit spacing throughout
- Use Inter for all text elements
- Meet WCAG AA contrast (4.5:1 minimum for body text)

DON'T:
- Invent colors outside the defined palette
- Use system-default blue (#0000EE) for links — use var(--color-primary)
- Apply border-radius values not on the brand scale
- Use font-weight below 400 or above 900

---
brand:
  name: "LangChain"
  category: "AI & Machine Learning"
  primary: "#4ADE80"
  secondary: "#1C3C3C"
  accent: "#FFFFFF"
typography:
  heading: "Inter, system-ui"
  headingWeight: 700
  headingTracking: "-0.02em"
  body: "Inter, system-ui"
  bodySize: "16px"
  lineHeight: 1.6
spacing:
  base: 4
  scale: [4, 8, 12, 16, 24, 32, 48, 64, 96]
shape:
  radiusSm: "4px"
  radiusMd: "6px"
  radiusLg: "16px"
  radiusXl: "24px"
---

# LangChain Design System
> AI Agent Context — read this entire file before generating any UI for LangChain
> Source: StyleExtract Vault · styleextract.com/vault/langchain

## Brand Overview
Dark with green accents — the developer framework for LLM applications.

## Color System

| Role      | Hex       | Usage                          |
|-----------|-----------|-------------------------------|
| Primary   | `#4ADE80` | CTAs, links, key accents  |
| Secondary | `#1C3C3C` | Backgrounds, headings    |
| Accent    | `#FFFFFF` | Highlights, badges, icons |
| Surface   | `#1C1C1E` | Card backgrounds |
| Border    | `#2C2C2E` | Dividers, outlines |

ALWAYS use `#4ADE80` for primary interactive elements and CTAs.
NEVER invent colors outside the palette above.

## Typography

- **Heading font**: Inter, system-ui
- **Heading weight**: 700 / letter-spacing −0.02em
- **Body font**: Inter, system-ui
- **Body size**: 16px / line-height 1.6

## Spacing System

Base unit is **4px**. Allowed values: 4, 8, 12, 16, 24, 32, 48, 64, 96px.
Never use arbitrary values.

## Component Patterns

### Buttons
```
Primary:   bg #4ADE80  · text #1D1D1F  · rounded-[6px]  · px-6 py-3  · font-semibold
Secondary: transparent    · border-[#4ADE80]       · text-[#4ADE80]      · px-6 py-3
```

### Cards
```
bg white (dark: #1C1C1E) · border #E5E5E7 (dark: #2C2C2E) · rounded-2xl · p-6 · shadow-sm
```

### Navigation
```
bg #1C3C3C · text #FFFFFF · h-[60px] · px-6 · logo-left · links-right
```

## Accessibility
- All text WCAG AA (4.5:1 minimum)
- Interactive targets: 44×44px minimum
- Never convey state via color alone

## Brand Voice
Dark with green accents — the developer framework for LLM applications.