With Version 8.7.0 Mermaid comes out with a system for dynamic and integrated configuration of themes. The intent is to increase the customizability and ease of styling for mermaid diagrams.
The theme can be altered by changing the root level variable `theme` variable in the configuration. To change it for the whole site you must use the `initialize` call. To do it for just for a single diagram you can use the `%%init%%` directive
Themes follow and build upon the Levels of Configuration, and employ `directives` to modify and create custom configurations, as they were introduced in Version [8.6.0](./8.6.0_docs.md).
## Deployable Themes
The following are a list of **Deployable themes**, sample `%%init%%` directives and `initialize` calls.
1.**base**- Designed to be modified, as the name implies it is supposed to be used as the base for making custom themes.
2.**forest**- A theme full of light greens that is easy on the eyes.
3.**dark**- A theme that would go well with other dark-colored elements.
4.**default**- The default theme for all diagrams.
5.**neutral**- The theme to be used for black and white printing.
## Site-wide Themes
Site-wide themes are declared via `initialize` by site owners.
Example of `Initialize` call setting `theme` to `base`:
```javascript
mermaidAPI.initialize({
securityLevel: 'loose',
theme: 'base',
});
```
**Notes**: Only site owners can use the `mermaidAPI.initialize` call, to set values. Site-Users will have to use `%%init%%` to modify or create the theme for their diagrams.
## Themes at the Local or Current Level
When Generating a diagram using on a webpage that supports mermaid. It is also possible to override site-wide theme settings locally, for a specific diagram, using directives, as long as it is not prohibited by the `secure` array.
Leaving it empty will set all variable values to default.
## Color and Color Calculation:
Color definitions have certain interactions in mermaid, this is in order to ensure visibility for diagrams. Mermaid will adjust some variables automatically, when colors are changed in order to compensate and maintain readability.
**The Default Value Column** to the right of the Variable column will denote the Variable paired/associated with the Variable on the left and the nature of this pairing or association. If it for instance says primaryColor it means that it gets primaryColor as default value. If it says "based on primaryColor" it means that it is calculated/ derived from primaryColor. This calculation can be primary color inversion, a change of hue, darkening or lightening by 10%, etc.
You can create your own themes, by changing any of the given variables below. If you are using a dark background, set dark mode to true to adjust the colors. It is possible to override the calculations using the variable names below, with `%%init%%` if you wish to style it differently.
## Theme Variables Reference Table
::: tip
Variables that are unique to some diagrams can be affected by changes in Theme Variables
:::
| Variable | Default/Base/Factor value | Calc | Description |
| primaryColor | #fff4dd | | Color to be used as background in nodes, other colors will be derived from this |
| primaryBorderColor | based on primaryColor | \* | Color to be used as border in nodes using primaryColor |
| primaryTextColor | based on darkMode #ddd/#333 | \* | Color to be used as text color in nodes using primaryColor |
| secondaryColor | based on primaryColor | \* | |
| secondaryBorderColor | based on secondaryColor | \* | Color to be used as border in nodes using secondaryColor |
| secondaryTextColor | based on secondaryColor | \* | Color to be used as text color in nodes using secondaryColor |
| tertiaryColor | based on primaryColor | \* | |
| tertiaryBorderColor | based on tertiaryColor | \* | Color to be used as border in nodes using tertiaryColor |
| tertiaryTextColor | based on tertiaryColor | \* | Color to be used as text color in nodes using tertiaryColor |
| noteBkgColor | #fff5ad | | Color used as background in notes |
| noteTextColor | #333 | | Text color in note rectangles. |
| noteBorderColor | based on noteBkgColor | \* | Border color in note rectangles. |
| lineColor | based on background | \* | |
| textColor | based on primaryTextColor | \* | Text in diagram over the background for instance text on labels and on signals in sequence diagram or the title in gantt diagram |
| mainBkg | based on primaryColor | \* | Background in flowchart objects like rects/circles, class diagram classes, sequence diagram etc |
| errorBkgColor | tertiaryColor | \* | Color for syntax error message |
| errorTextColor | tertiaryTextColor | \* | Color for syntax error message |
# What follows are Variables, specific to different diagrams and charts.
## Some Theme Variables serve as, or affect the Default Values for Specific Diagram Variables, unless changed using `%%init%%` .
The Theming Engine does not admit color codes and will only accept proper color values. Color Names is not supported so for instance, the color value 'red' will not work, but '#ff0000' will work.
# Common theming activities
## How to change the color of the arrows
# Examples:
When adjusting a theme it might be helpful to look at how your preferred theme goes with the diagrams, to evaluate whether everything is visible and looks good.
In the following examples, the directive `init` is used, with the `theme` being declared as `neutral`. For more information on using directives, read the documentation for [Version 8.6.0](/8.6.0_docs.md)
