how to make scroller show only on hover of container

1.scrollbox {
2  width: 100px;
3  height: 100px;
4  overflow: auto;
5  visibility: hidden;
6}
7
8.scrollbox-content,
9.scrollbox:hover,
10.scrollbox:focus {
11  visibility: visible;
12}
13
14.scrollbox_delayed {
15  transition: visibility 0.2s;
16}
17
18.scrollbox_delayed:hover {
19  transition: visibility 0s 0.2s;
20}