I think that as long as your top step is at least as thick as your smaller steps and of ply or solid wood you'll be okay. If solid wood have the grain running east to west for strength as per the smaller steps in your pic above.
Thanks
@hugo7 started
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I think that as long as your top step is at least as thick as your smaller steps and of ply or solid wood you'll be okay. If solid wood have the grain running east to west for strength as per the smaller steps in your pic above.