Don't use inline <style> elements for custom CSS

using a <link rel="stylesheet"/> has two main advantages:

  1. it allows the browser to cache the stylesheet when viewing multiple post on the same blog, improving load times.
  2. it allows multiple blogs to use the same stylesheet without copy/pasting via clever use of css @import. this prevents the two blogs from having their stylesheet go out of sync, and also saves a tiny bit of server space (also, the stylesheet will be cached between blogs)