Code blocks in Posts

Created by: matyus

Summary

There seems to be inconsistency in how code blocks are formatted between various posts.

Expected result

Code blocks should use the same syntax and the output should have syntax highlighting.

Actual result

Some code blocks are syntax highlighted and some aren't.

• Markdown style indent: https://github.com/a11yproject/a11yproject.com/blob/00d814701f2559afbb8f764ab9fbb84cd020bc53/_posts/2013-01-11-how-to-hide-content.md#L22-L28
• Three backticks: https://github.com/a11yproject/a11yproject.com/blob/00d814701f2559afbb8f764ab9fbb84cd020bc53/_posts/2013-01-14-aria-landmark-roles.md#L76-L78
• Three backticks with syntax highlighting: https://github.com/a11yproject/a11yproject.com/blob/00d814701f2559afbb8f764ab9fbb84cd020bc53/_posts/2013-01-14-never-use-maximum-scale.md#L21-L23
• Liquid syntax highlight: https://github.com/a11yproject/a11yproject.com/blob/00d814701f2559afbb8f764ab9fbb84cd020bc53/_posts/2013-05-11-skip-nav-links.md#L20-L34

Additional Information

I'm interested in contributing to this repo and happy to open a pull request to tidy the code up! Just let me know if I should account for anything in particular... it's not immediately obvious to me how any of this relates to the 2019 redesign.

I would like to propose the use of three back ticks with the filetype (e.g. ```html) rather than plain markdown style double indents or liquid tags.