Fix gaps in blog posts

[lepisma]

Being converted from pure markdown, the blog posts are not picking up style classes from the main css and so have poor gaps between divs and table items. Example:

Two solutions:

1. Add the required classes in the markdown files themselves.
2. Add css for blog posts (preferred)

[lepisma]

Note to self:
The best way is to import the sass from spectre and extend the classes. The problem right now is that spectre was in less at 846353cb40512404c5b8d27084a6fbe7b4a47d23. Should migrate to recent version of spectre.