::-webkit-scrollbar addresses the background of the bar itself. It is usually covered by the other elements
::-webkit-scrollbar-button addresses the directional buttons on the scrollbar
::-webkit-scrollbar-track addresses the empty space “below” the progress bar
::-webkit-scrollbar-track-piece is the top-most layer of the the progress bar not covered by the draggable scrolling element (thumb)
::-webkit-scrollbar-thumb addresses the draggable scrolling element that resizes depending on the size of the scrollable element
::-webkit-scrollbar-corner addresses the (usually) bottom corner of the scrollable element, where two scrollbars might meet
::-webkit-resizer addresses the draggable resizing handle that appears above the scrollbar-corner at the bottom corner of some elements