Overview

Feather can render Mermaid diagrams and KaTeX math expressions directly in the preview pane. Both features are toggleable in Settings > Diagrams & Math.

Mermaid Diagrams

Use fenced code blocks with the language set to mermaid:

```mermaid
graph TD
    A[Start] --> B{Decision}
    B -->|Yes| C[Do something]
    B -->|No| D[Do something else]
```

Supported Diagram Types

• Flowcharts (graph TD, graph LR)
• Sequence diagrams
• State diagrams
• Gantt charts
• Pie charts
• Class diagrams
• Entity relationship diagrams
• Any other Mermaid-supported diagram type

Theme Integration

• Diagram colors automatically match your current preview theme
• Each of the 9 built-in themes has its own set of Mermaid color variables
• Diagrams render with transparent backgrounds so they blend with the preview

Export

Mermaid diagrams are included when exporting to PDF or HTML. They render as inline SVG in the output.

KaTeX Math

Feather supports LaTeX math notation via KaTeX.

Inline Math

Wrap expressions in single dollar signs:

The equation $E = mc^2$ describes mass-energy equivalence.

Block / Display Math

Wrap expressions in double dollar signs on their own lines:

$$
\int_0^\infty e^{-x^2} dx = \frac{\sqrt{\pi}}{2}
$$

Supported Notation

KaTeX covers standard LaTeX math, including:

• Fractions: \frac{a}{b}
• Integrals: \int, \sum, \prod
• Matrices: \begin{bmatrix}...\end{bmatrix}
• Greek letters: \alpha, \beta, \gamma, etc.
• Operators, subscripts, superscripts, and more

For the full list, see the KaTeX supported functions.

Export

• PDF and HTML: Math renders fully in the output
• Word (DOCX): Math is converted to formatted text where possible