Check out example codes for "css overflow-y scroll". It will help you in understanding the concepts better.

Code Example 1

div.ex1 {
  overflow-y: scroll;
}

div.ex2 {
  overflow-y: hidden;
}

div.ex3 {
  overflow-y: 
    auto;
}

div.ex4 {
  overflow-y: visible;
}

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