Improve readability of text and code blocks in blog posts

[ee7]

#259 is a huge improvement, but I've always thought that there's something else about text and code blocks in Nim blog posts that decreases readability.

As an example, compare:

• https://nim-lang.org/blog/2020/10/16/version-140-released.html
• https://github.com/nim-lang/website/blob/master/jekyll/_posts/2020-10-16-version-140-released.md#gc-orc

I find it much easier to read on GitHub. Do others agree?

Some suggestions:

1. Make headers at the level of "Known incompatibilities and gotchas" and "Deepcopy" more obvious - it's currently much harder to distinguish sections than on GitHub.
2. Add horizontal padding inside inline code blocks, and have a bigger difference between the font faces. The code blocks in the bottom image below tend to blend into the regular text.

Maybe people have some other suggestions.

Somewhat related: #202

[narimiran]

Make headers at the level of "Known incompatibilities and gotchas" and "Deepcopy" more obvious - it's currently much harder to distinguish sections than on GitHub.

Agreed. I'll work on this.