Update index.html

Author: mulle-nat

index.html

@@ -148,7 +148,7 @@ <h2>+[mulle-objc support]</h2>
       Thanks to our Sponsor(s) for supporting the project.
       <p>
         <table>
-        <tr><td><a href="https://www.jetbrains.com">Jetbrains</a></td><td><a href="https://www.jetbrains.com"><img src="//raw.githubusercontent.com/mulle-objc/mulle-objc.github.io/master/pix/jetbrains.svg" alt="Jetbrains" height=64></a></td></tr>
+        <tr><td><a href="https://www.jetbrains.com">Jetbrains</a></td><td><a href="https://www.jetbrains.com"><img src="//raw.githubusercontent.com/mulle-objc/mulle-objc.github.io/master/pix/jetbrains.svg" alt="Jetbrains" height=48></a></td></tr>
         </table>
       </section>
     </section>