Hi, KittyCatS team! This is a suggestion for the website, not for KittyCatS themselves.
The new version of Safari in El Capitan allows for "pinned" tabs. These tabs don't use the favicon but rather an SVG file linked to in the header of a page:
Code:
<link rel="mask-icon" href="website_icon.svg" color="red">
Here's the link with more information.
If the SVG file isn't present, Safari just shows the first letter of the website name (in this case, a plain K). It'd be nice to see the KittyCatS logo instead.
Cheers!