Replace SyntaxHighlighter with prism.js. SyntaxHighlighter does not seem
to be maintained. Prism.js seems a nice alternative with support for
Ruby, javascript, erb and yaml. Prism.js uses the MIT License.
https://github.com/PrismJS/prism

For bash a customized definition of the bash+shell-session themes is
used with the following comamnds  added commands:
brew, bundle, cat, git, gem, rackup, rake, rails, ruby, rubocop and
  yarn