how to change scroolbar css code example

Example: custom scrollbar

::-webkit-scrollbar              { /* 1 */ }
::-webkit-scrollbar-button       { /* 2 */ }
::-webkit-scrollbar-track        { /* 3 */ }
::-webkit-scrollbar-track-piece  { /* 4 */ }
::-webkit-scrollbar-thumb        { /* 5 */ }
::-webkit-scrollbar-corner       { /* 6 */ }
::-webkit-resizer                { /* 7 */ }


/* Different States */
:horizontal
:vertical
:decrement
:increment
:start
:end 
:double-button
:single-button
:no-button
:corner-present
:window-inactive


/* All toghether example */
::-webkit-scrollbar-track-piece:start {
   /* Select the top half (or left half) or scrollbar track individually */
}

::-webkit-scrollbar-thumb:window-inactive {
   /* Select the thumb when the browser window isn't in focus */
}

::-webkit-scrollbar-button:horizontal:decrement:hover {
   /* Select the down or left scroll button when it's being hovered by the mouse */
}


/* Example */
body::-webkit-scrollbar {
    width: 1em;
}
body::-webkit-scrollbar-track {
    -webkit-box-shadow: inset 0 0 6px rgba(0,0,0,0.3);
}
body::-webkit-scrollbar-thumb {
  background-color: darkgrey;
  outline: 1px solid slategrey;
}