Retyle monospace/code-examples

The two things which were noticible as I read through the docs were:

• The inline code examples (using backticks in the markdown) have a font which is too large.
• The code boxes look chunky and also have too large of a font.

Compare this, for example, with the way that GitLab renders the same markdown. While the inline code snippets may stand out a little too much due to their red font, I think it is still nicer than the default Jekyll rendering on our page. Also, while the black background for the code examples may draw too much attention, I prefer the non-rounded corners, the smaller padding, and the way the font is sized similar to the regular text:

Thoughts? Changes are easy to implement, but feedback would be great.