I understand this design, but I saw such a case . I do not understand why is 是 at the end of the sentence . Can you explain please
Random chunks of language, without context, are difficult to fathom. You should post the context where you found this scrap of language, at least the sentence before and the sentence after.
Unless one is a René Descartes (je pense donc je suis) one is hardly likely to go around saying "你是。", but in the right context, a lonely “你是。” may be enough said。
You haven't changed, you still always come late!
Two years (we have) not seen each other,
I wouldn't have thought he'd have changed so much,
(he's) a lot thinner than before,
but (what) hasn't changed is,
he is still friendly, happy and concerned about others.
和以前一样的是 --> [他还是那么热情、快乐、关心别人.]
The basic sentence with all details stripped away is 你是， "you are". 跟以前一样 is adding detail saying "as before/ as usual".
的 connects the detail phrase to the basic sentence. So the total sentence would mean "You are the same as always/usual/etc".
In this case 是 is not serving as any kind of grammatical accent, but just as the basic definition-- an equivalent to english am/is/are. The reason its at the end of the sentence is just a coincidence of it being the only character in the predicate/verb area this time.