Alpine is a theme for Tumblr. Check out a live demo here. Alpine looks something like this:
Responsive photosets had been the bane of my existence since day one. For most of Alpine's existence, I was using a hacky method that simply took the raw images from the photosets and arranged them using floats and stuff. However, it wouldn't allow you to click on the photos to enlarge, and was a bit slow. But now, thanks to the new {Photoset} tag, they're responsive! (Previously, photosets looked like {Photoset-700} with a fixed dimension.) This is exciting stuff!
I've worked hard to make video as close to responsive as possible. This works better for certain video aspects than others, but it works.
Alpine allows for some visual customization, allowing users to set background images and accent colors.
Tumblr CSS goes at the beginning of the file (or inline). It sucks.
This is the worst part about developing Tumblr themes, in my opinion. Tumblargh wasn't useful for me. I'm going to try some of the strategies outlined here next. Until then, it's not fun.