Thin scrollbar, visible on hover

In some situations, the default browser scrollbars are too bulky and ugly. I did not know that there is an option to make them thinner, also visible only on hover:

.scrollbar {
    scrollbar-color: transparent transparent;
    scrollbar-width: thin;
}
.scrollbar.visible, .scrollbar:hover {
    scrollbar-color: #aaa transparent;
}

Thanks, Reddit!