Actually, they call it “Appearance”. It’s a new feature on the Tumblr mobile app that lets you customize how your Tumblr blog will look within the app. Most blogs have clean, uncluttered designs when viewed on small devices. The theme used on a standard web page often doesn’t work on a phone’s smaller screen. Well, Tumblr has found a way you can give your Tumblr blog a bit of mobile style that doesn’t impact its viewability.
The things you can change are the background color and accent color, header image, avatar image and shape (square or round) and font for the blog’s title and description. Here’s a quick walk-thru . . .
Your changes won’t be visible in the reader until someone taps on an item to see the article at your blog, but it’s still an easy and fun way to jazz up your Tumblr’s mobile look. And, since most Tumblr’s use their phone to keep up with their reading, you’re readers will appreciate your efforts.