Default

%%{init: { 'logLevel': 0, 'theme': 'default'} }%%
  graph TD
            A(Start) --> B[/Another/]
            A[/Another/] --> C[End]
            subgraph section
              B
              C
            end

Forest

%%{init: { 'logLevel': 1, 'theme': 'forest'} }%%
  graph TD
            A(Start) --> B[/Another/]
            A[/Another/] --> C[End]
            subgraph section
              B
              C
            end

Neutral

%%{init: { 'logLevel': 1, 'theme': 'neutral'} }%%
  graph TD
            A(Start) --> B[/Another/]
            A[/Another/] --> C[End]
            subgraph section
              B
              C
            end

Dark

%%{init: { 'logLevel': 1, 'theme': 'dark'} }%%
  graph TD
            A(Start) --> B[/Another/]
            A[/Another/] --> C[End]
            subgraph section
              B
              C
            end

Base with overriding themeVariable

%%{init: { 'theme': 'base', 'themeVariables':{ 'primaryColor': '#ff0000'}}}%%

  graph TD
            A(Start) --> B[/Another/]
            A[/Another/] --> C[End]
            subgraph section
              B
              C
            end

Nothing set, should be Default

%%{init: { 'logLevel': 1} }%%

  graph TD
            A(Start) --> B[/Another/]
            A[/Another/] --> C[End]
            subgraph section
              B
              C
            end