chore: adjust venn graph

Author: tianzhou

mintlify/introduction/what-is-bytebase.mdx

@@ -36,7 +36,12 @@ This workflow governs how your database data is accessed, replacing the need for
 
 In short, Bytebase unifies the process of **changing the database** with the **process of accessing its data**, giving you a single pane of glass for true database DevSecOps.
 
-<img src="/content/docs/what-is-bytebase/venn.webp" alt="venn" width="300" />
+<img
+  src="/content/docs/what-is-bytebase/venn.webp"
+  alt="venn"
+  width="400"
+  style={{ display: 'block', margin: '0 auto' }}
+/>
 
 ## Demo Bytebase