Data Element for Subclass

Hi there, 

I'm trying to capture the subclass of a html on a row of icons. What would the appropriate DOM attribute be to capture the value in bold red (def) when clicked?

div.buttons.mt-4.mx-auto.abc > div > div.abc.def

div.buttons.mt-4.mx-auto.abc > div > div.abc.ghi

div.buttons.mt-4.mx-auto.abc > div > div.abc.jkl

I've tried doing this previously, and I've managed two outcomes:

1) Captured only the parent class (abc)

2) Successfully capturing both class (abc def) but only the first value (abc def) even though I've clicked the subsequent icons (abc ghi / abc jkl) 

Are there any suggestions on how I can successful tag the buttons either with Launch settings or custom code? Appreciated!