add feature entry, switch to neutral theme, remove border

Author: silverwind

docs/content/page/index.en-us.md

@@ -128,6 +128,7 @@ Windows, on architectures like amd64, i386, ARM, PowerPC, and others.
     - Environment variables
     - Command line options
 - Multi-language support ([21 languages](https://github.com/go-gitea/gitea/tree/master/options/locale))
+- [Mermaid](https://mermaidjs.github.io/) Diagram support
 - Mail service
     - Notifications
     - Registration confirmation

web_src/js/markdown/mermaid.js

@@ -5,7 +5,11 @@ export async function renderMermaid(els) {
 
   const {mermaidAPI} = await import(/* webpackChunkName: "mermaid" */'mermaid');
 
-  mermaidAPI.initialize({startOnLoad: false});
+  mermaidAPI.initialize({
+    startOnLoad: false,
+    theme: 'neutral',
+    securityLevel: 'strict',
+  });
 
   for (const el of els) {
     mermaidAPI.render(`mermaid-${random(12)}`, el.textContent, (svg) => {

web_src/less/_markdown.less

@@ -502,6 +502,4 @@
     padding: 1rem;
     margin: 1rem 0;
     border-radius: .25rem;
-    background: #fff;
-    border: 1px solid #d4d4d5;
 }