Narrow Widths for a few Column Filter Input Boxes

Gandac

DataTables 1.10.4

My table will eventually have more than 100 rows. Here is a link http://www.stockportwalkers.org.uk/development/walking_routes_w_datatables.html

I would like to make the widths of the column filter input boxes narrower for a few columns in my table. For example the data in one of the columns is a single character. From tests I have done it seems to me that the minimum width of the input box is fixed. This means that some of my columns are far too wide for the data. Is it possible to make these columns much narrower? Can it be done in CSS rather than jQuery (thinking of maintenance)?

Thank you.