First off, nice work, this is legit useful stuff.

Suggestions; the regex reference could use a distinguishing feature such as a subtle light grey background and/or a line seperating it along with more whitespace.

Also, the boxes seem arbitrarily placed. I realize one is centered, and the others take up the remaining space on the next "line", but perhaps you could create better visual boundaries or something.

Lastly, apologies, but maybe the font Lato looks nice on your setup, but its rather jaggedy/unappealing on windows.