How do I keep the div height when there is continous number of element added in the div?

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CSS

CSS3

I have a program that spawns an element p every seconds and its parent container has a size of 600px, then whenever element p have overtaken the parent container height of 600px it lengthen the height of its parent container which I don't want. I want it to keep on adding element p every seconds but won't show the element p who exceeds the parent container border.

What I have tried:

I've tried clip-path but that does not work.