With the updates in Tangent v0.6.0-alpha.6, you can now pretty easily make a custom style that transforms your #writing manuscript to look more like a proper book.
This is normal markdown text, with normal blank lines in between paragraphs. Tangent adds css classes to empty lines that the example custom style shrinks down, creating an awesome book-like effect.
The best part is that this can be applied to only a sub-folder of your workspace!