This is not perfect: we don't try to detect cases such as «$((ls); (ls))», which look like arithmetic expansions but are in fact command substitutions. Fixes part of #607. Introduces #704.
zsh-syntax-highlighting / highlighters
Navigate into the individual highlighters' documentation to see
what styles ($ZSH_HIGHLIGHT_STYLES keys) each highlighter defines.
Refer to the documentation on highlighters for further information.