Allow customizing mermaid configuration

CHANGELOG.rst

@@ -14,6 +14,7 @@ Changelog
 - gemify plugin to use it with Gemfile.local or other plugins
 - remove spam protection functionality
 - Chart.js 2.9.4 support
+- Allow overwrite mermaid theme and variables
 
 3.0.0
 +++++

app/views/additionals/settings/_additionals.html.slim

@@ -1,7 +1,7 @@
 ' Need Help? :
-= link_to(l(:label_additionals_doc),
-          'https://additionals.readthedocs.io/en/latest/',
+= link_to l(:label_additionals_doc), 'https://additionals.readthedocs.io/en/latest/',
           class: 'external',
           target: '_blank',
-          rel: 'noopener')
+          rel: 'noopener'
+
 = render_tabs additionals_settings_tabs

assets/javascripts/mermaid_load.js

@@ -1,5 +1,16 @@
 $(function() {
-  mermaid.initialize({ startOnLoad: true,
-                       theme: 'default',
-                       themeVariables: { 'fontSize': '12px' } });
+  if (globalThis !== undefined && globalThis.mermaidTheme !== undefined) {
+    var mermaidTheme = globalThis.mermaidTheme;
+  } else {
+    var mermaidTheme = 'default';
+  }
+  if (globalThis !== undefined && globalThis.mermaidThemeVariables !== undefined) {
+    var mermaidThemeVariables = globalThis.mermaidThemeVariables;
+  } else {
+    var mermaidThemeVariables = { 'fontSize': '12px' };
+  }
+  mermaid.initialize({
+    startOnLoad: true,
+    theme: mermaidTheme,
+    themeVariables: mermaidThemeVariables });
 });