Make the Scylla Mascot on the header not transparent

![image](https://user-images.githubusercontent.com/9107969/138937589-0e5b80ac-8956-42e2-912b-02ce7af7d0d4.png)

Set the mascot opacity to 1 (non transparent).

Reported by @tzach 