I think you will be glad to hear this because there is a relatively simple fix for this problem. You will need some scraps of 3/4″, 5/8″, 1/2″, 3/8″, 1/4″, 1/8″ luan. Glue & screw the 3/4″ to the first step, 5/8″ to the second, 1/2″ to the third & so on. In this fashion you will make up the difference in the riser height (step height is rise & depth is run) & still be within the code allowance of up to 3/8″ variation in riser height. but best of all you will not notice the difference when walking up & down the stairs. Another common problem I see with rough framed stairs is that the installer forgot or didn’t know to cut the tread thickness off of the bottom of the first stair. This will give you a first step that is an 1-1/2″ taller than the rest of the steps (if you use 1-1/2″ treads) & a last step that is 1-1/2″ shorter. In this case you would be better off removing the stairs to correct the problem, but I am glad we have another option for you.