For exactly that reason, we used $$(inline expression) and $$$(block expression) for the KaTeX delimiters in a web-based Markdown editor that I worked on.
Originally we used the "standard" single $ delimiter but would run into problems when someone's content included a string like, "...between $190 and $200...". It wasn't elegant, but saved a lot of complicated parsing to look for whitespace or other implicit indications of what the author was trying to do.
Originally we used the "standard" single $ delimiter but would run into problems when someone's content included a string like, "...between $190 and $200...". It wasn't elegant, but saved a lot of complicated parsing to look for whitespace or other implicit indications of what the author was trying to do.