Styling

D2 provides various styling options to customize the appearance of your diagrams.

Fill Color

node: Node {
  style.fill: "#e3f2fd"
}

Common colors:

success: Success { style.fill: "#c8e6c9" }
warning: Warning { style.fill: "#fff3e0" }
error: Error { style.fill: "#ffcdd2" }
info: Info { style.fill: "#e3f2fd" }

Stroke (Border)

node: Node {
  style.stroke: "#1976d2"
  style.stroke-width: 2
}

Dashed Borders

planned: Planned {
  style.stroke-dash: 5
}

Border Radius

rounded: Rounded {
  style.border-radius: 10
}

Opacity

faded: Faded {
  style.opacity: 0.5
}

Font Styling

node: Node {
  style.font-size: 20
  style.font-color: "#333"
  style.bold: true
  style.italic: true
}

Shadow

elevated: Elevated {
  style.shadow: true
}

Multiple Styles

styled: Styled Node {
  style.fill: "#e8f5e9"
  style.stroke: "#4caf50"
  style.stroke-width: 2
  style.border-radius: 8
  style.shadow: true
}

Edge Styling

a -> b: {
  style.stroke: "#f44336"
  style.stroke-width: 3
}

Animated Edges

a -> b: {
  style.animated: true
}

Dashed Edges

a -> b: {
  style.stroke-dash: 5
}

Classes

Define reusable styles with classes:

classes: {
  primary: {
    style.fill: "#1976d2"
    style.font-color: white
  }
  success: {
    style.fill: "#4caf50"
    style.font-color: white
  }
  danger: {
    style.fill: "#f44336"
    style.font-color: white
  }
}

button1: Primary Button { class: primary }
button2: Success Button { class: success }
button3: Danger Button { class: danger }

Multiple Classes

classes: {
  rounded: {
    style.border-radius: 20
  }
  elevated: {
    style.shadow: true
  }
}

fancy: Fancy { class: [rounded, elevated] }

Container Styling

Containers can be styled like nodes:

public: Public Zone {
  style.fill: "#e8f5e9"
  style.stroke: "#4caf50"
  style.stroke-width: 2

  server: Server
}

private: Private Zone {
  style.fill: "#fff3e0"
  style.stroke: "#ff9800"
  style.stroke-width: 2

  database: Database
}

Pattern: Status Colors

classes: {
  running: {
    style.fill: "#c8e6c9"
    style.stroke: "#4caf50"
  }
  stopped: {
    style.fill: "#ffcdd2"
    style.stroke: "#f44336"
  }
  pending: {
    style.fill: "#fff3e0"
    style.stroke: "#ff9800"
  }
}

service1: Service 1 { class: running }
service2: Service 2 { class: stopped }
service3: Service 3 { class: pending }

Pattern: Network Zones

dmz: DMZ {
  style.fill: "#fff8e1"
  style.stroke: "#ffc107"
  style.stroke-width: 2
  style.stroke-dash: 5

  lb: Load Balancer
}

internal: Internal {
  style.fill: "#e8f5e9"
  style.stroke: "#4caf50"
  style.stroke-width: 2

  app: Application
  db: Database
}

Pattern: Highlighted Path

a -> b -> c -> d

# Highlight the critical path
b -> c: {
  style.stroke: "#f44336"
  style.stroke-width: 3
  style.animated: true
}

Pattern: Deprecated Elements

current: Current API {
  style.fill: "#e3f2fd"
}

deprecated: Deprecated API {
  style.fill: "#f5f5f5"
  style.stroke: "#9e9e9e"
  style.font-color: "#9e9e9e"
  style.stroke-dash: 5
}

current -> deprecated: migration

Color Reference

Material Design Colors

# Red
#ffcdd2 (light), #f44336 (main), #b71c1c (dark)

# Green
#c8e6c9 (light), #4caf50 (main), #1b5e20 (dark)

# Blue
#e3f2fd (light), #1976d2 (main), #0d47a1 (dark)

# Orange
#fff3e0 (light), #ff9800 (main), #e65100 (dark)

# Yellow
#fff8e1 (light), #ffc107 (main), #ff6f00 (dark)

# Grey
#f5f5f5 (light), #9e9e9e (main), #424242 (dark)

Best Practices

1. Use color meaningfully - Reserve red for errors, green for success, etc.

2. Don't over-style - Clean diagrams are easier to read

3. Use classes for consistency - Define styles once, use everywhere

4. Consider accessibility - Don't rely solely on color for meaning

5. Match your brand - Use company colors where appropriate