Theme Configuration

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With Version 8.7.0 Mermaid comes out with a system for dynamic and integrated configuration of the diagram themes. The objective of this is to increase the customizability of mermaid and the ease of Styling, with the customization of themes through the %%init%% directive and initialize calls.

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.

**These Theming Configurations, similar to directives, will also be made applicable in the Live-Editor, to maximize customizability.

Site-wide Themes

Site-wide themes are still declared via initialize by site owners.

Example of Initalize call setting theme to base:

    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.

%%{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:

%%{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

Making a Custom Theme 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%%.

%%{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

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

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.

primaryColor

#fff4dd

Color to be used as background in nodes, other colors will be derived from this

fontFamily

“trebuchet ms”, verdana, arial

fontSize

16px

Font Size, in pixels

secondaryColor

based on primaryColor

*

tertiaryColor

based on primaryColor

*

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

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

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

labelBoxBkgColor

actorBkg

*

Label Box Background Color

signalColor

textColor

*

Signal Color

signalTextColor

textColor

*

Signal Text 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%%.

%%{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

**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

%%{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

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

%%{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
%%{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

Flowchart (beta)

%%{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

Sequence diagram

%%{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

Class diagram

%%{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()
	}

Gantt

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

State diagram

%%{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 --> [*]

State diagram (beta)

%%{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 --> [*]

Entity Relations diagram

      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"

User journey diagram

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