how to add a scrollbar in html code example

Example 1: custom scrollbar

body::-webkit-scrollbar {
  width: 12px;               /* width of the entire scrollbar */
}
body::-webkit-scrollbar-track {
  background: orange;        /* color of the tracking area */
}
body::-webkit-scrollbar-thumb {
  background-color: blue;    /* color of the scroll thumb */
  border-radius: 20px;       /* roundness of the scroll thumb */
  border: 3px solid orange;  /* creates padding around scroll thumb */
}

Example 2: change scrollbar color

.scrollable-element {
  scrollbar-color: red yellow; /* red is for the thumb and yellow is for the track */
}