How do you adjust the width of the column containing the row numbers?

When I have 1000 rows or more, the column shows "1.." making it difficult to figure out the row numbers.
How can I adjust the width of that column?

Thanks!

.active-scroll-left, .active-scroll-corner {width: 45px}
.active-scroll-top, .active-scroll-data {padding-left: 45px}

http://activewidgets.com/grid.howto.style.headers/row-header-width.html