diff --git a/src/node/markdown/markdown.ts b/src/node/markdown/markdown.ts
index bc1c3898..60fec621 100644
--- a/src/node/markdown/markdown.ts
+++ b/src/node/markdown/markdown.ts
@@ -287,6 +287,13 @@ export const createMarkdownRenderer = async (
       md.use(mathPlugin.default ?? mathPlugin, {
         ...(typeof options.math === 'boolean' ? {} : options.math)
       })
+      const orig = md.renderer.rules.math_block!
+      md.renderer.rules.math_block = (tokens, idx, options, env, self) => {
+        return orig(tokens, idx, options, env, self).replace(
+          /^<mjx-container /,
+          '<mjx-container tabindex="0" '
+        )
+      }
     } catch (error) {
       throw new Error(
         'You need to install `markdown-it-mathjax3` to use math support.'