Better readability of the code blocks (inline and code fences)

[msurguy]

To increase readability of the code within the tutorials, need the following:

• Add spacing after each code block (code fence), see screenshot below
• Make the inline code more readable by copying Github's style for the inline code (add padding, different font-size and distinct background color for inline code)

@gohai This is for me to keep track of the issue and I'll fix this. Let me know if you have any thoughts against :)