Mermaid

```mermaid
graph TB
    c1-->a2
    subgraph one
    a1-->a2
    end
    subgraph two
    b1-->b2
    end
    subgraph three
    c1-->c2
    end
```
  

graph TB c1-->a2 subgraph one a1-->a2 end subgraph two b1-->b2 end subgraph three c1-->c2 end

Optional settings

Theme initialize mermaid with default configuration ({}), You can custom config like this:

mermaid:
  initialize:
    startOnLoad: true
    logLevel: fatal
    flowchart:
      diagramPadding: 8
      htmlLabels: true
      curve: linear
    gantt:
      titleTopMargin: 25
    .
    .
    .
  

Tip

The theme chooses the stable version of mermaid, if you want to use the custom mermaid, add following configuration

mermaid:
  custom: https://cdn.jsdelivr.net/npm/mermaid/dist/mermaid.min.js
  

Mermaid documentation, see: https://mermaid-js.github.io/mermaid/