When I add a subscript to a primed variable, the subscript is rendered lower than when it is a subscript to an unprimed variable.
For example, when I compile
$l_x l'_x l_x l'_x l_x l'_x$
The subscript x is at a different height for the primed variables and the unprimed ones.
Any one have any idea why this is happening? And how I can fix this so that the subscript of the primed variable appears at the same height? (Or am I doing something wrong?)