Theme Configuration

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.

Deployable Themes

The following are a list of Deployable themes, sample %%init%% directives and initialize calls.

base- Designed to be modified, as the name implies it is supposed to be used as the base for making custom themes.
forest- A theme full of light greens that is easy on the eyes.
dark- A theme that would go well with other dark-colored elements.
default- The default theme for all diagrams.
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.

mermaid

%%{init: {'theme':'base'}}%%
  graph TD
    a --> b

Here is an example of how %%init%% can set the theme to 'base', this assumes that themeVariables are set to default:

Code:

mermaid

%%{init: {'theme':'base'}}%%
        graph TD
          A[Christmas] -->|Get money| B(Go shopping)
          B --> C{Let me think}
          B --> G[/Another/]
          C ==>|One| D[Laptop]
          C -->|Two| E[iPhone]
          C -->|Three| F[fa:fa-car Car]
          subgraph section
            C
            D
            E
            F
            G
          end

Render:

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List of Themes

Customizing Themes with `themeVariables`

The easiest way to make a custom theme is to start with the base theme, and just modify theme variables through themeVariables, via %%init%%.

Parameter	Description	Type	Required	Objects contained
themeVariables	Array containing objects, modifiable with the `%%init%%` directive	Array	Required	primaryColor, lineColor, textColor

Here is an example of overriding primaryColor through themeVariables and giving everything a different look, using %%init%%.

Code:

mermaid

%%{init: {'theme': 'base', 'themeVariables': { 'primaryColor': '#ff0000'}}}%%
        graph TD
          A[Christmas] -->|Get money| B(Go shopping)
          B --> C{Let me think}
          B --> G[/Another/]
          C ==>|One| D[Laptop]
          C -->|Two| E[iPhone]
          C -->|Three| F[fa:fa-car Car]
          subgraph section
            C
            D
            E
            F
            G
          end

Render:

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Notes: 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

NOTE

Variables that are unique to some diagrams can be affected by changes in Theme Variables }

Variable	Default/Base/Factor value	Calc	Description
darkMode	false		Boolean Value that dictates how to calculate colors. "true" will activate darkmode.
background	#f4f4f4		Used to calculate color for items that should either be background colored or contrasting to the background.
fontFamily	"trebuchet ms", verdana, arial
fontSize	16px		Font Size, in pixels
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%%` .

Flowchart

Variable	Default/ Associated Value	Calc	Description
nodeBorder	primaryBorderColor	*	Node Border Color
clusterBkg	tertiaryColor	*	Background in subgraphs
clusterBorder	tertiaryBorderColor	*	Cluster Border Color
defaultLinkColor	lineColor	*	Link Color
titleColor	tertiaryTextColor	*	Title Color
edgeLabelBackground	based on secondaryColor	*
nodeTextColor	primaryTextColor	*	Color for text inside Nodes.

sequence diagram

name	Default value	Calc	Description
actorBorder	primaryBorderColor	*	Actor Border Color
actorBkg	mainBkg	*	Actor Background Color
actorTextColor	primaryTextColor	*	Actor Text Color
actorLineColor	grey	*	Actor Line Color
signalColor	textColor	*	Signal Color
signalTextColor	textColor	*	Signal Text Color
labelBoxBkgColor	actorBkg	*	Label Box Background Color
labelBoxBorderColor	actorBorder	*	Label Box Border Color
labelTextColor	actorTextColor	*	Label Text Color
loopTextColor	actorTextColor	*	Loop ext Color
activationBorderColor	based on secondaryColor	*	Activation Border Color
activationBkgColor	secondaryColor	*	Activation Background Color
sequenceNumberColor	based on lineColor	*	Sequence Number Color

state colors

name	Default value	Calc	Description
labelColor	primaryTextColor	*
altBackground	tertiaryColor	*	Used for background in deep composite states

class colors

name	Default value	Calc	Description
classText	textColor	*	Color of Text in class diagrams

User journey colors

name	Default value	Calc	Description
fillType0	primaryColor	*	Fill for 1st section in journey diagram
fillType1	secondaryColor	*	Fill for 2nd section in journey diagram
fillType2	based on primaryColor	*	Fill for 3rd section in journey diagram
fillType3	based on secondaryColor	*	Fill for 4th section in journey diagram
fillType4	based on primaryColor	*	Fill for 5th section in journey diagram
fillType5	based on secondaryColor	*	Fill for 6th section in journey diagram
fillType6	based on primaryColor	*	Fill for 7th section in journey diagram
fillType7	based on secondaryColor	*	Fill for 8th section in journey diagram

**Notes: Values are meant to create an alternating look.

Here is an example of overriding `primaryColor` and giving everything a different look, using `%%init%%`.

Code:

mermaid

%%{init: {'theme': 'base', 'themeVariables': { 'primaryColor': '#ff0000'}}}%%
        graph TD
          A[Christmas] -->|Get money| B(Go shopping)
          B --> C{Let me think}
          B --> G[/Another/]
          C ==>|One| D[Laptop]
          C -->|Two| E[iPhone]
          C -->|Three| F[fa:fa-car Car]
          subgraph section
            C
            D
            E
            F
            G
          end

Render:

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**This got a bit too dark and bit too colorful. With some easy steps this can be fixed:

Make the primary color a little lighter
set the tertiary color to a reddish shade as well
make the edge label background differ from the subgraph by setting the edgeLabelBackground

Code:

mermaid

%%{init: {'theme': 'base', 'themeVariables': { 'primaryColor': '#ffcccc', 'edgeLabelBackground':'#ffffee', 'tertiaryColor': '#fff0f0'}}}%%
        graph TD
          A[Christmas] -->|Get money| B(Go shopping)
          B --> C{Let me think}
          B --> G[/Another/]
          C ==>|One| D[Laptop]
          C -->|Two| E[iPhone]
          C -->|Three| F[fa:fa-car Car]
          subgraph section
            C
            D
            E
            F
            G
          end

Render:

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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 base. For more information on using directives, read the documentation for Version 8.6.0

Flowchart

Code:

mermaid

%%{init: {'securityLevel': 'loose', 'theme':'base'}}%%
        graph TD
          A[Christmas] -->|Get money| B(Go shopping)
          B --> C{Let me think}
          B --> G[/Another/]
          C ==>|One| D[Laptop]
          C -->|Two| E[iPhone]
          C -->|Three| F[fa:fa-car Car]
          subgraph section
            C
            D
            E
            F
            G
          end

Render:

null

Flowchart (beta)

Code:

mermaid

%%{init: {'securityLevel': 'loose', 'theme':'base'}}%%
        flowchart TD
          A[Christmas] -->|Get money| B(Go shopping)
          B --> C{Let me think}
          B --> G[Another]
          C ==>|One| D[Laptop]
          C x--x|Two| E[iPhone]
          C o--o|Three| F[fa:fa-car Car]
          subgraph section
            C
            D
            E
            F
            G
          end

Render:

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Sequence diagram

Code:

mermaid

%%{init: {'securityLevel': 'loose', 'theme':'base'}}%%
        sequenceDiagram
          autonumber
          par Action 1
            Alice->>John: Hello John, how are you?
          and Action 2
            Alice->>Bob: Hello Bob, how are you?
          end
          Alice->>+John: Hello John, how are you?
          Alice->>+John: John, can you hear me?
          John-->>-Alice: Hi Alice, I can hear you!
          Note right of John: John is perceptive
          John-->>-Alice: I feel great!
              loop Every minute
                John-->Alice: Great!
            end

Render:

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Class diagram

Code:

mermaid

%%{init: {'securityLevel': 'loose', 'theme':'base'}}%%

classDiagram
	Animal "1" <|-- Duck
	Animal <|-- Fish
	Animal <--o Zebra
	Animal : +int age
	Animal : +String gender
	Animal: +isMammal()
	Animal: +mate()
	class Duck{
		+String beakColor
		+swim()
		+quack()
	}
	class Fish{
		-int sizeInFeet
		-canEat()
	}
	class Zebra{
		+bool is_wild
		+run()
	}

Render:

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Gantt

Code:

mermaid

gantt
       dateFormat                YYYY-MM-DD
       title                     Adding GANTT diagram functionality to mermaid
       excludes                  :excludes the named dates/days from being included in a charted task..
       section A section
       Completed task            :done,    des1, 2014-01-06,2014-01-08
       Active task               :active,  des2, 2014-01-09, 3d
       Future task               :         des3, after des2, 5d
       Future task2              :         des4, after des3, 5d

       section Critical tasks
       Completed task in the critical line :crit, done, 2014-01-06,24h
       Implement parser and jison          :crit, done, after des1, 2d
       Create tests for parser             :crit, active, 3d
       Future task in critical line        :crit, 5d
       Create tests for renderer           :2d
       Add to mermaid                      :1d

       section Documentation
       Describe gantt syntax               :active, a1, after des1, 3d
       Add gantt diagram to demo page      :after a1  , 20h
       Add another diagram to demo page    :doc1, after a1  , 48h

       section Last section
       Describe gantt syntax               :after doc1, 3d
       Add gantt diagram to demo page      :20h
       Add another diagram to demo page    :48h

Render:

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State diagram

Code:

mermaid

%%{init: {'securityLevel': 'loose', 'theme':'base'}}%%
      stateDiagram
        [*] --> Active

        state Active {
            [*] --> NumLockOff
            NumLockOff --> NumLockOn : EvNumLockPressed
            NumLockOn --> NumLockOff : EvNumLockPressed
            --
            [*] --> CapsLockOff
            CapsLockOff --> CapsLockOn : EvCapsLockPressed
            CapsLockOn --> CapsLockOff : EvCapsLockPressed
            --
            [*] --> ScrollLockOff
            ScrollLockOff --> ScrollLockOn : EvCapsLockPressed
            ScrollLockOn --> ScrollLockOff : EvCapsLockPressed
        }
        state SomethingElse {
          A --> B
          B --> A
        }

        Active --> SomethingElse
        note right of SomethingElse : This is the note to the right.

        SomethingElse --> [*]

Render:

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State diagram (beta)

Code:

mermaid

%%{init: {'securityLevel': 'loose', 'theme':'base'}}%%
stateDiagram-v2
        [*] --> Active

        state Active {
            [*] --> NumLockOff
            NumLockOff --> NumLockOn : EvNumLockPressed
            NumLockOn --> NumLockOff : EvNumLockPressed
            --
            [*] --> CapsLockOff
            CapsLockOff --> CapsLockOn : EvCapsLockPressed
            CapsLockOn --> CapsLockOff : EvCapsLockPressed
            --
            [*] --> ScrollLockOff
            ScrollLockOff --> ScrollLockOn : EvCapsLockPressed
            ScrollLockOn --> ScrollLockOff : EvCapsLockPressed
        }
        state SomethingElse {
          A --> B
          B --> A
        }

        Active --> SomethingElse2
        note right of SomethingElse2 : This is the note to the right.

        SomethingElse2 --> [*]

Render:

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Entity Relations diagram

Code:

mermaid

      erDiagram
        CUSTOMER }|..|{ DELIVERY-ADDRESS : has
        CUSTOMER ||--o{ ORDER : places
        CUSTOMER ||--o{ INVOICE : "liable for"
        DELIVERY-ADDRESS ||--o{ ORDER : receives
        INVOICE ||--|{ ORDER : covers
        ORDER ||--|{ ORDER-ITEM : includes
        PRODUCT-CATEGORY ||--|{ PRODUCT : contains
        PRODUCT ||--o{ ORDER-ITEM : "ordered in"

Render:

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User journey diagram

Code:

mermaid

journey
            title My working day
            section Go to work
              Make tea: 5: Me
              Go upstairs: 3: Me
              Do work: 1: Me, Cat
            section Go home
              Go downstairs: 5: Me
              Sit down: 5: Me

Render:

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Theme Configuration #

Deployable Themes #

Site-wide Themes #

Themes at the Local or Current Level #

Code:

Render:

List of Themes #

Customizing Themes with themeVariables #

Code:

Render:

Color and Color Calculation: #

Theme Variables Reference Table #

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%% . #

Flowchart #

sequence diagram #

state colors #

class colors #

User journey colors #

Here is an example of overriding primaryColor and giving everything a different look, using %%init%%. #

Code:

Render:

Code:

Render:

Common theming activities #

How to change the color of the arrows #

Examples: #

Flowchart #

Code:

Render:

Flowchart (beta) #

Code:

Render:

Sequence diagram #

Code:

Render:

Class diagram #

Code:

Render:

Gantt #

Code:

Render:

State diagram #

Code:

Render:

State diagram (beta) #

Code:

Render:

Entity Relations diagram #

Code:

Render:

User journey diagram #

Code:

Render:

Theme Configuration

Deployable Themes

Site-wide Themes

Themes at the Local or Current Level

List of Themes

Customizing Themes with `themeVariables`

Color and Color Calculation:

Theme Variables Reference Table

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%%` .

Flowchart

sequence diagram

state colors

class colors

User journey colors

Here is an example of overriding `primaryColor` and giving everything a different look, using `%%init%%`.

Common theming activities

How to change the color of the arrows

Examples:

Flowchart

Flowchart (beta)

Sequence diagram

Class diagram

Gantt

State diagram

State diagram (beta)

Entity Relations diagram

User journey diagram