mermaid/docs/breakingChanges.md

Breaking changes

Breaking changes from history version to latest version:

#1

mermaid.initialize({
    sequenceDiagram:{
        ...
    }
})

has been changed to

mermaid.initialize({
    sequence:{
        ...
    }
})

#2

In old versions you need to add CSS file to your HTML:

<link rel="stylesheet" href="mermaid.min.css">

or

<link rel="stylesheet" href="mermaid.forest.min.css">

Now it is not needed to do so. And there are no more CSS files in distrubtion files.

You just

mermaid.initialize({
    theme: 'forest'
})

and it works like a charm.

This is because now the CSS is inline with SVG for portability.