`nanoscroller.css` has the above CSS like this:

```
.nano:hover > .pane, .pane.active, .pane.flashed {
  visibility : visible\9; /* Target only IE7 and IE8 with this hack */
  opacity    : 0.99;
}
```

Your changes compile to a very different result:

```
.nano:hover > .pane,
.nano.visible > .pane,
.nano:hover .pane.active,
.nano.visible .pane.active,
.nano:hover .pane.flashed,
.nano.visible .pane.flashed {
  visibility: visible\9; /* Target only IE7 and IE8 with this hack */
  opacity: 0.99;
}
```