Well spotted, blackrockrose. It's part of a package of changes I'm making, but so far it's gone live only at the alternate site,
www.chihuahua-puzzle.com. I'll spell out what's changed when it's fully implemented on both sites.
As for the icon, you're right: the animal is meant to be a chihuahua. I've noticed that on mobile phones and tablets the icon on the browser tab is usually tiny, and difficult to recognise. Many of the most successful websites use a stylised version of their initial letter - e.g. Facebook, Amazon, Google, Netflix. Since Chihuahua is all about letters, the C icon seems a logical way to go.
More info over the next few days.