Version 8.7.0: Theme Configuration

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
%%{init: {'theme': 'base', 'themeVariables': { 'primaryColor': '#00ff00'}}}%% 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 coloumn 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 nodesusing 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 nodesusing 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 nodesusing tertiaryColor
noteBkgColor #fff5ad   Color used as background in notes
noteTextColor #333   Text color in note rectangless.
noteBorderColor based on noteBkgColor * Border color in note rectangless.
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
%%{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 teriary color to a redish 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
%%{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)

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

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
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

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 --> [*]

%%{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 --> [*]
%%{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"
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
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