[drewschrauf]

Nice! Just a couple of minor nitpicks:

1. The delay between updating the regex/test text and seeing the result is a little long. I find regex tools much more useful if I can see the results change as I'm typing.

2. I did a simple regex with two capture groups and the second backreference came up red in the matches box. As soon as I see red, I assume there's an error. Might be worth removing those "danger colours" from the list.

Other than that, looking good!