Since you’re editing a parent selector (as shown by the amber outline and “Back” button above your class field) this is just letting you know that the top margin style you’ve applied to the paren class is being overwritten by one of your combo classes:
The element your editing (which I’m just guessing is the same one I used in my screenshot above) actually has two additional combo classes applied to it—so while the more specific “Section” class has 20px of top margin, one of the other combo classes is overwriting it.
If you were to edit this top margin when it’s crossed out, it will be overridden by the 0px style that’s applied with one of the combo classes—which happens to be the “color empatie” class:
Anytime you see a blue class label, that style is being applied by the chosen class on the active breakpoint, so removing that 0px style would fall back to the “relative” class (since this also has a 0px top margin applied to it):
I’d recommend watching out for these unnecessary styles as they lead to larger CSS file sizes and make it more difficult to change styles down the road.
Hopefully that helps