Hello,

This can already be achieved using a "custom format" ;-)

In the options (click on the gear icon in the upper right corner of ETU), set something like this in the "Custom format" field: https://gist.githubusercontent.com/alct/8674d11a7a8a605371b6928c420c8209/raw/0dbb92938230327cada9eb92a601fb755b388598/gistfile1.txt

And save your file with the ".html" extension.