Update sponsor.mdx

Author: Jason3S

website/src/pages/sponsor.mdx

@@ -44,7 +44,7 @@ In order to dedicate resources to maintaining and improving the CSpell suite of
     src="https://github.com/sponsors/streetsidesoftware/card"
     title="Sponsor streetsidesoftware"
     width="100%"
-    style={{ border: 0 }}
+    style={{ border: 0, 'border-radius': '10px' }}
 ></iframe>
 
 {/* [![GitHub Sponsor](https://img.shields.io/badge/-black?style=social&logo=githubsponsors&label=GitHub%20Sponsor%3A%20Street%20Side%20Software)](https://github.com/sponsors/streetsidesoftware) */}