Hi there!You're right, Target applies offers using CSS selectors. You
can use unique ids for each of the elements you're modifying using
Target. Alternately, make sure the element can be uniquely accessed
using a hierarchy of classes. Also, see that the 'Use element IDs' and
'Use element Classes' toggles are turned on in your Site Preferences.
You can check that by going to Configure -> Site Preferences in VEC.You
can find more on how Adobe Target generates a selector for an element -