message: Update single post styling
diff: //
  > .post-header
  - collapsed-margins(2em)
  + collapsed-margins(6em)
  > .post-category-title
  // No top margin because of hidden image
  - margin 0 0 2em 0
  + margin 0 0 1.5em 0
  +
  + > h1:first-child
  + font-size font-size-h6
  + text-transform uppercase
  + font-weight bold
  + margin-bottom 0.5em
  > h1
  margin 0
  - text-align center
  - font-size font-size-h2
  - font-weight normal
  + text-align left
  + font-size font-size-h3
  + font-weight bold
  > .post-author
  > .post-meta
  - text-align center
  + text-align left
  font-size font-size-base
  line-height line-height-base
  - > .post-author
  - font-weight bold
  -
  > .post-content
  margin-bottom 8em
  position relative
  