I’ve been wanting to create a tool like this for a while, and finally had the need for it recently, to develop a more complex theme. Based on an old project called 
HTMLhouse, here’s 
CSShorse – a CSS editor for WriteFreely blogs with a real-time preview.
To use it, head to css.horse, enter in your blog URL, and press Go. The app will load your live site on the right, and any custom styles in the editor on the left. As you change those styles, you’ll be able to preview the changes in real-time (just beware: changes do not automatically save). Then when you have something you like, just copy and paste the entire stylesheet into your blog’s Custom CSS section and save those changes!
Hope you enjoy! If you have any feedback or ideas, I’d love to hear them.
