Spacing around blog post texts

[ewels]

I personally find the spacing around the body text in blog posts a bit tight, making it feel crowded and difficult to read.

Suggestions:

1. Hide the blog link sidebar on narrower screens (just tweak the breakpoints to use xxl instead of xl)
2. Stick the ToC to the far right on wider screens
3. Consider pushing up the maximum width a little

I know @mashehu doesn't like wide text columns, and I have a feeling that the ToC may have previously been on the right and felt lost. So I don't really care much about the first two. But tweaking the sidebar breakpoint should be simple and would help a lot for folks like me who like to work on small windows on small laptop screens.