CSS customized scroll bar in div

Question

How can I customize a scroll bar via CSS (Cascading Style Sheets) for one div and not the whole page?

Answer 1

.className::-webkit-scrollbar {
  width: 10px;
  background-color: rgba(0,0,0,0);
}

.className::-webkit-scrollbar-thumb {
  background: rgba(255, 255, 255, 0.5);
  border-radius: 5px;
}

gave me a nice mobile/osx like one.